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Thursday, October 6, 2022

Cascading failure

From Wikipedia, the free encyclopedia
 
An animation demonstrating how a single failure may result in other failures throughout a network.

A cascading failure is a failure in a system of interconnected parts in which the failure of one or few parts leads to the failure of other parts, growing progressively as a result of positive feedback. This can occur when a single part fails, increasing the probability that other portions of the system fail. Such a failure may happen in many types of systems, including power transmission, computer networking, finance, transportation systems, organisms, the human body, and ecosystems.

Cascading failures may occur when one part of the system fails. When this happens, other parts must then compensate for the failed component. This in turn overloads these nodes, causing them to fail as well, prompting additional nodes to fail one after another.

In power transmission

Cascading failure is common in power grids when one of the elements fails (completely or partially) and shifts its load to nearby elements in the system. Those nearby elements are then pushed beyond their capacity so they become overloaded and shift their load onto other elements. Cascading failure is a common effect seen in high voltage systems, where a single point of failure (SPF) on a fully loaded or slightly overloaded system results in a sudden spike across all nodes of the system. This surge current can induce the already overloaded nodes into failure, setting off more overloads and thereby taking down the entire system in a very short time.

This failure process cascades through the elements of the system like a ripple on a pond and continues until substantially all of the elements in the system are compromised and/or the system becomes functionally disconnected from the source of its load. For example, under certain conditions a large power grid can collapse after the failure of a single transformer.

Monitoring the operation of a system, in real-time, and judicious disconnection of parts can help stop a cascade. Another common technique is to calculate a safety margin for the system by computer simulation of possible failures, to establish safe operating levels below which none of the calculated scenarios is predicted to cause cascading failure, and to identify the parts of the network which are most likely to cause cascading failures.

One of the primary problems with preventing electrical grid failures is that the speed of the control signal is no faster than the speed of the propagating power overload, i.e. since both the control signal and the electrical power are moving at the same speed, it is not possible to isolate the outage by sending a warning ahead to isolate the element.

Examples

Cascading failure caused the following power outages:

In computer networks

Cascading failures can also occur in computer networks (such as the Internet) in which network traffic is severely impaired or halted to or between larger sections of the network, caused by failing or disconnected hardware or software. In this context, the cascading failure is known by the term cascade failure. A cascade failure can affect large groups of people and systems.

The cause of a cascade failure is usually the overloading of a single, crucial router or node, which causes the node to go down, even briefly. It can also be caused by taking a node down for maintenance or upgrades. In either case, traffic is routed to or through another (alternative) path. This alternative path, as a result, becomes overloaded, causing it to go down, and so on. It will also affect systems which depend on the node for regular operation.

Symptoms

The symptoms of a cascade failure include: packet loss and high network latency, not just to single systems, but to whole sections of a network or the internet. The high latency and packet loss is caused by the nodes that fail to operate due to congestion collapse, which causes them to still be present in the network but without much or any useful communication going through them. As a result, routes can still be considered valid, without them actually providing communication.

If enough routes go down because of a cascade failure, a complete section of the network or internet can become unreachable. Although undesired, this can help speed up the recovery from this failure as connections will time out, and other nodes will give up trying to establish connections to the section(s) that have become cut off, decreasing load on the involved nodes.

A common occurrence during a cascade failure is a walking failure, where sections go down, causing the next section to fail, after which the first section comes back up. This ripple can make several passes through the same sections or connecting nodes before stability is restored.

History

Cascade failures are a relatively recent development, with the massive increase in traffic and the high interconnectivity between systems and networks. The term was first applied in this context in the late 1990s by a Dutch IT professional and has slowly become a relatively common term for this kind of large-scale failure.

Example

Network failures typically start when a single network node fails. Initially, the traffic that would normally go through the node is stopped. Systems and users get errors about not being able to reach hosts. Usually, the redundant systems of an ISP respond very quickly, choosing another path through a different backbone. The routing path through this alternative route is longer, with more hops and subsequently going through more systems that normally do not process the amount of traffic suddenly offered.

This can cause one or more systems along the alternative route to go down, creating similar problems of their own.

Related systems are also affected in this case. As an example, DNS resolution might fail and what would normally cause systems to be interconnected, might break connections that are not even directly involved in the actual systems that went down. This, in turn, may cause seemingly unrelated nodes to develop problems, that can cause another cascade failure all on its own.

In December 2012, a partial loss (40%) of Gmail service occurred globally, for 18 minutes. This loss of service was caused by a routine update of load balancing software which contained faulty logic—in this case, the error was caused by logic using an inappropriate 'all' instead of the more appropriate 'some'. The cascading error was fixed by fully updating a single node in the network instead of partially updating all nodes at one time.

Cascading structural failure

Certain load-bearing structures with discrete structural components can be subject to the "zipper effect", where the failure of a single structural member increases the load on adjacent members. In the case of the Hyatt Regency walkway collapse, a suspended walkway (which was already overstressed due to an error in construction) failed when a single vertical suspension rod failed, overloading the neighboring rods which failed sequentially (i.e. like a zipper). A bridge that can have such a failure is called fracture critical, and numerous bridge collapses have been caused by the failure of a single part. Properly designed structures use an adequate factor of safety and/or alternate load paths to prevent this type of mechanical cascade failure.

Other examples

Biology

Biochemical cascades exist in biology, where a small reaction can have system-wide implications. One negative example is ischemic cascade, in which a small ischemic attack releases toxins which kill off far more cells than the initial damage, resulting in more toxins being released. Current research is to find a way to block this cascade in stroke patients to minimize the damage.

In the study of extinction, sometimes the extinction of one species will cause many other extinctions to happen. Such a species is known as a keystone species.

Electronics

Another example is the Cockcroft–Walton generator, which can also experience cascade failures wherein one failed diode can result in all the diodes failing in a fraction of a second.

Yet another example of this effect in a scientific experiment was the implosion in 2001 of several thousand fragile glass photomultiplier tubes used in the Super-Kamiokande experiment, where the shock wave caused by the failure of a single detector appears to have triggered the implosion of the other detectors in a chain reaction.

Finance

In finance, the risk of cascading failures of financial institutions is referred to as systemic risk: the failure of one financial institution may cause other financial institutions (its counterparties) to fail, cascading throughout the system. Institutions that are believed to pose systemic risk are deemed either "too big to fail" (TBTF) or "too interconnected to fail" (TICTF), depending on why they appear to pose a threat.

Note however that systemic risk is not due to individual institutions per se, but due to the interconnections. Frameworks to study and predict the effects of cascading failures have been developed in the research literature.

A related (though distinct) type of cascading failure in finance occurs in the stock market, exemplified by the 2010 Flash Crash.

Interdependent cascading failures

Illustration of the interdependent relationship among different infrastructures

Diverse infrastructures such as water supply, transportation, fuel and power stations are coupled together and depend on each other for functioning, see Fig. 1. Owing to this coupling, interdependent networks are extremely sensitive to random failures, and in particular to targeted attacks, such that a failure of a small fraction of nodes in one network can trigger an iterative cascade of failures in several interdependent networks. Electrical blackouts frequently result from a cascade of failures between interdependent networks, and the problem has been dramatically exemplified by the several large-scale blackouts that have occurred in recent years. Blackouts are a fascinating demonstration of the important role played by the dependencies between networks. For example, the 2003 Italy blackout resulted in a widespread failure of the railway network, health care systems, and financial services and, in addition, severely influenced the telecommunication networks. The partial failure of the communication system in turn further impaired the electrical grid management system, thus producing a positive feedback on the power grid. This example emphasizes how inter-dependence can significantly magnify the damage in an interacting network system.

Model for overload cascading failures

A model for cascading failures due to overload propagation is the Motter–Lai model.

Geopolymer cement

From Wikipedia, the free encyclopedia

Geopolymer cement is a binding system that hardens at room temperature.

List of the minerals, chemicals used for making geopolymer cements

It is a more environmentally friendly alternative to conventional Portland cement. It relies on minimally processed natural materials or industrial byproducts to significantly reduce the carbon footprint of cement production, while also being highly resistant to many common concrete durability issues.

Geopolymer cements exist which may cure more rapidly than Portland-based cements.

Production

Production of geopolymer cement requires an aluminosilicate precursor material such as metakaolin or fly ash, a user-friendly alkaline reagent (for example, sodium or potassium soluble silicates with a molar ratio MR SiO2:M2O ≥ 1.65, M being Na or K) and water (See the definition for "user-friendly" reagent below). Room temperature hardening is more readily achieved with the addition of a source of calcium cations, often blast furnace slag.

Geopolymer cements can be formulated to cure more rapidly than Portland-based cements; some mixes gain most of their ultimate strength within 24 hours. However, they must also set slowly enough that they can be mixed at a batch plant, either for precasting or delivery in a concrete mixer. Geopolymer cement also has the ability to form a strong chemical bond with silicate rock-based aggregates. In March 2010, the US Department of Transportation Federal Highway Administration released a TechBrief titled Geopolymer Concrete that states:

The production of versatile, cost-effective geopolymer cements that can be mixed and hardened essentially like Portland cement would represent a game changing advancement, revolutionizing the construction of transportation infrastructure and the building industry.

Geopolymer concrete

There is often confusion between the meanings of the terms 'geopolymer cement' and 'geopolymer concrete'. A cement is a binder, whereas concrete is the composite material resulting from the mixing and hardening of cement with water (or an alkaline solution in the case of geopolymer cement), and stone aggregates. Materials of both types (geopolymer cements and geopolymer concretes) are commercially available in various markets internationally. 

Chemistry: Portland cement vs Geopolymer cement

Portland cement chemistry compared to geopolymerization GP

Left: hardening of Portland cement (P.C.) through hydration of calcium silicate into calcium silicate hydrate (C-S-H) and portlandite, Ca(OH)2.

Right: hardening (setting) of geopolymer cement (GP) through poly-condensation of potassium oligo-(sialate-siloxo) into potassium poly(sialate-siloxo) cross linked network.

If a geopolymer compound requires heat setting it is not called geopolymer cement but rather geopolymer binder.

Alkali-activated materials vs. geopolymer cements.

Geopolymerization chemistry requires appropriate terminologies and notions that are evidently different from those in use by Portland cement experts. The main article geopolymer summarizes how geopolymer cements belong to the category of inorganic polymer. On this matter, the Australian Geopolymer Alliance outlines on its web site the following statement: "Joseph Davidovits developed the notion of a geopolymer (a Si/Al inorganic polymer) to better explain these chemical processes and the resultant material properties. To do so required a major shift in perspective, away from the classical crystalline hydration chemistry of conventional cement chemistry. To date this shift has not been well accepted by practitioners in the field of alkali activated cements who still tend to explain such reaction chemistry in Portland cement terminology.

Indeed, geopolymer cement is sometimes mistaken for alkali-activated cement and concrete, developed more than 50 years ago by V.D. Glukhovsky in Ukraine, the former Soviet Union. They were originally known under the names "soil silicate concretes" and "soil cements". Because Portland cement concretes can be affected by the deleterious Alkali-aggregate reaction, coined AAR or Alkali-silica reaction coined ASR (see for example the RILEM Committee 219-ACS Aggregate Reaction in Concrete Structures), the wording alkali-activation has a negative impact on civil engineers. However, geopolymer cements do not in general show these deleterious reactions (see below in Properties), when an appropriate aggregate is selected - geopolymers can also work in acidic mediums, further disassociating them from AAM. In addition, alkali-activated materials are not polymers, so they cannot be called and mistaken for geopolymers. Indeed, the polymer chemistry is radically different compared to the calcium hydrate or precipitate chemistry. Nevertheless, several cement scientists continue to promote the terminology related to alkali-activated materials or alkali-activated geopolymers. These cements, abbreviated AAM, encompass the specific fields of alkali-activated slags, alkali-activated coal fly ashes, and various blended cementing systems (see RILEM Technical committee 247-DTA).

User-friendly alkaline-reagents

List of user-hostile and user-friendly chemical reagents

Although geopolymerization does not rely on toxic organic solvents but only on water, it needs chemical ingredients that may be dangerous and therefore requires some safety procedures. Material Safety rules classify the alkaline products in two categories: corrosive products (named here: hostile) and irritant products (named here: friendly). The two classes are recognizable through their respective logos.

The table lists some alkaline chemicals and their corresponding safety label. The corrosive products must be handled with gloves, glasses and masks. They are user-hostile and cannot be implemented in mass applications without the appropriate safety procedures. In the second category one finds Portland cement or hydrated lime, typical mass products. Geopolymeric alkaline reagents belonging to this class may also be termed as User-friendly, although the irritant nature of the alkaline component and the potential inhalation risk of powders still require the selection and use of appropriate personal protective equipment, as in any situation where chemicals or powders are handled.

The development of so-called alkali-activated-cements or alkali-activated geopolymers (the latter considered by some to be incorrect terminology), as well as several recipes found in the literature and on the Internet, especially those based on fly ashes, use alkali silicates with molar ratios SiO2:M2O below 1.20, or systems based on pure NaOH (8M or 12M). These conditions are not user-friendly for the ordinary labor force, and require careful consideration of personal protective equipment if employed in the field. Indeed, laws, regulations, and state directives push to enforce for more health protections and security protocols for workers’ safety.

Conversely, Geopolymer cement recipes employed in the field generally involve alkaline soluble silicates with starting molar ratios ranging from 1.45 to 1.95, particularly 1.60 to 1.85, i.e. user-friendly conditions. It may happen that for research, some laboratory recipes have molar ratios in the 1.20 to 1.45 range.

Geopolymer cement categories

Categories of geopolymer cement include:

  • Slag-based geopolymer cement.
  • Rock-based geopolymer cement.
  • Fly ash-based geopolymer cement
    • type 1: alkali-activated fly ash geopolymer.
    • type 2: slag/fly ash-based geopolymer cement.
  • Ferro-sialate-based geopolymer cement.

Slag-based geopolymer cement

Components: metakaolin (MK-750) + blast furnace slag + alkali silicate (user-friendly).

Geopolymeric make-up: Si:Al = 2 in fact solid solution of Si:Al=1, Ca-poly(di-sialate) (anorthite type) + Si:Al =3 , K-poly(sialate-disiloxo) (orthoclase type) and C-S-H Ca-silicate hydrate.

The first geopolymer cement developed in the 1980s was of the type (K,Na,Ca)-poly(sialate) (or slag-based geopolymer cement) and resulted from the research developments carried out by Joseph Davidovits and J.L. Sawyer at Lone Star Industries, USA and yielded the invention of Pyrament® cement. The American patent application was filed in 1984 and the patent US 4,509,985 was granted on April 9, 1985, with the title 'Early high-strength mineral polymer'.

Rock-based geopolymer cement

The replacement of a certain amount of MK-750 with selected volcanic tuffs yields geopolymer cement with better properties and less CO2 emission than the simple slag-based geopolymer cement.

Manufacture components: metakaolin MK-750, blast furnace slag, volcanic tuffs (calcined or not calcined), mine tailings and alkali silicate (user-friendly).

Geopolymeric make-up: Si:Al = 3, in fact solid solution of Si:Al=1 Ca-poly(di-sialate) (anorthite type) + Si:Al =3–5 (Na,K)-poly(silate-multisiloxo) and C-S-H Ca-silicate hydrate.

Fly ash-based geopolymer cements

Later on, in 1997, building on the works conducted on slag-based geopolymeric cements, on the one hand and on the synthesis of zeolites from fly ashes on the other hand, Silverstrim et al. and van Jaarsveld and van Deventer developed geopolymeric fly ash-based cements. Silverstrim et al. US Patent 5,601,643 was titled 'Fly ash cementitious material and method of making a product'.

Presently, there are two types based on siliceous (EN 197) or Class F (ASTM C618) fly ashes:

  • Type 1: alkali-activated fly ash geopolymer (user-hostile):
In many cases requires heat curing at 60–80°C; not manufactured separately as a cement, but rather produced directly as a fly-ash based concrete. NaOH (user-hostile) + fly ash: partially-reacted fly ash particles embedded in an alumino-silicate gel with Si:Al= 1 to 2, zeolitic type (chabazite-Na and sodalite) structures.
  • Type 2: slag/fly ash-based geopolymer cement (user-friendly):
Room-temperature cement hardening. User-friendly silicate solution + blast furnace slag + fly ash: fly ash particles embedded in a geopolymeric matrix with Si:Al= 2, (Ca,K)-poly(sialate-siloxo).

Ferro-sialate-based geopolymer cement

The properties are similar to those of rock-based geopolymer cement but involve geological elements with high iron oxide content. The geopolymeric make up is of the type poly(ferro-sialate) (Ca,K)-(-Fe-O)-(Si-O-Al-O-). This user-friendly geopolymer cement is in the development and commercialization phase.

CO2 emissions during manufacture

According to the Australian concrete expert B. V. Rangan, the growing worldwide demand for concrete is a great opportunity for the development of geopolymer cements of all types, with their lower release of carbon dioxide CO2 during production.

CO2 emissions contrasted

The manufacture of Portland cement clinker involves the calcination of calcium carbonate according to the reactions:

3CaCO3 + SiO2 → Ca3SiO5 + 3CO2
2CaCO3 + SiO2 → Ca2SiO4 + 2CO2

Reactions involving alumina also lead the formation of the aluminate and ferrite components of the clinker.

The production of 1 tonne of Portland clinker directly generates approximately 0.55 tonnes of chemical CO2, directly as a product of these reactions, and requires the combustion of carbonaceous fuel to yield approximately an additional 0.40 tonnes of carbon dioxide, although this is being reduced through gains in process efficiency and the use of waste as fuels. However, in total, 1 tonne of Portland cement leads to the emission of 0.8–1.0 tonnes of carbon dioxide.

Comparatively, Geopolymer cements do not rely on calcium carbonate as a key ingredient, and generate much less CO2 during manufacture, i.e. a reduction in the range of 40% to 80–90%. Joseph Davidovits delivered the first paper on this subject in March 1993 at a symposium organized by the American Portland Cement Association, Chicago, Illinois.

The Portland cement industry reacted strongly by lobbying the legal institutions to deliver CO2 emission numbers that did not include the part related to calcium carbonate decomposition, focusing only on combustion emission. An article written in the scientific magazine New Scientist in 1997 stated that: ...estimates for CO2 emissions from cement production have concentrated only on the former source [fuel combustion]. The UN’s Intergovernmental Panel on Climate Change puts the industry’s total contribution to CO2 emissions at 2.4 %; the Carbon Dioxide Information Analysis Center at the Oak Ridge National Laboratory in Tennessee quotes 2.6 %. Now Joseph Davidovits of the Geopolymer Institute... has for the first time looked at both sources. He has calculated that world cement production of 1.4 billion tonnes a year produces 7 % of [world] current CO2 emissions. Fifteen years later (2012), the situation has worsened with Portland cement CO2 emissions approaching 3 billion tonnes a year.

Comparative energy use

The energy needs and CO2 emissions for regular Portland cement, rock-based geopolymer cements and fly ash-based geopolymer cements. The comparison proceeds between Portland cement and geopolymer cements with similar strength, i.e. average 40 MPa at 28 days. There have been several studies published on the subject that may be summarized in the following way:

Rock-based geopolymer cement manufacture involves:

  • 70% by weight geological compounds (calcined at 700°C)
  • blast furnace slag
  • alkali-silicate solution (industrial chemical, user-friendly).

The presence of blast furnace slag provides room-temperature hardening and increases the mechanical strength.

Energy needs and CO2 emissions for 1 tonne of Portland cement and Rock-based Geopolymer cement
Energy needs (MJ/tonne) Calcination Crushing Silicate Sol. Total Reduction
Portland Cement 4270 430 0 4700 0
GP-cement, slag by-product 1200 390 375 1965 59%
GP-cement, slag manufacture 1950 390 375 2715 43%
CO2 emissions (tonne)




Portland Cement 1.000 0.020
1.020 0
GP-cement, slag by-product 0.140 0,018 0.050 0.208 80%
GP-cement, slag manufacture 0.240 0.018 0.050 0.308 70%

Energy needs

According to the US Portland Cement Association (2006), energy needs for Portland cement is in the range of 4700 MJ/tonne (average). The calculation for Rock- based geopolymer cement is performed with following parameters:

- the blast furnace slag is available as by-product from the steel industry (no additional energy needed);
- or must be manufactured (re-smelting from non granulated slag or from geological resources).

In the most favorable case — slag availability as by-product — there is a reduction of 59% of the energy needs in the manufacture of Rock-based geopolymer-cement in comparison with Portland cement. In the least favorable case —slag manufacture — the reduction reaches 43%.

CO2 emissions during manufacture

In the most favorable case — slag availability as by-product — there is a reduction of 80% of the CO2 emission during manufacture of Rock-based geopolymer cement in comparison with Portland cement. In the least favorable case —slag manufacture — the reduction reaches 70%.

Fly ash-based cements Class F fly ashes

They do not require any further heat treatment. The calculation is therefore easier. One achieves emissions in the range of 0.09 to 0.25 tonnes of CO2 / 1 tonne of fly ash-based cement, i.e. CO2 emissions that are reduced in the range of 75 to 90%.

Workability issues

Generally, one of the main problems with geopolymer binder is its poor workability: Alkali-activated Fly Ash has a much greater plastic viscosity than OPC and is prone to fast setting. In a matter of minutes, it can produce “highly viscous, unmanageable concrete mixtures”.

These problems were faced with Portland cement as well, leading to the development of mix designs and admixtures that increase workability; to a limited extent, those techniques can be applied to geopolymer binder.

File:Slump and Compressive Strength Values for Geopolymer Concrete with Superplasticizer Admixtures

Experimental evidence suggests that there are numerous ways to enhance geopolymer workability:

  • Using different combinations of precursor and activator
  • Adjusting the activator concentration and the ratio of activator to precursor
  • Increasing the water/binder ratio (as in Portland cement, this will increase workability and decrease concrete strength, which can then be counteracted by strength-enhancing measures such as heat curing)
  • Adding certain conventional superplasticizers to certain precursors/activator combinations
  • Adding newly developed superplasticizers for geopolymer binder (such as Alccofine, ground granulated blast-furnace slag, glass powder and rice husk)

Using these techniques, geopolymer binder has been shown to be suitable for both high-strength concrete applications as well as for self-compacting concrete.

Properties for Rock-based geopolymer cement (Ca,K)-poly(sialate-disiloxo)

  • shrinkage during setting: < 0.05%, not measurable.
  • compressive strength (uniaxial): > 90 MPa at 28 days (for high early strength formulation, 20 MPa after 4 hours).
  • flexural strength: 10–15 MPa at 28 days (for high early strength of 10 MPa after 24 hours).
  • Young Modulus: > 2 GPa.
  • freeze-thaw: mass loss < 0.1% (ASTM D4842), strength loss <5 % after 180 cycles.
Alkali-aggregate reaction comparison, Geopolymer cement vs. Portland cement, ASTM C227
  • wet-dry: mass loss < 0.1% (ASTM D4843).
  • leaching in water, after 180 days: K2O < 0.015%.
  • water absorption: < 3%, not related to permeability.
  • hydraulic permeability: 10−10 m/s.
  • sulfuric acid, 10%: mass loss 0.1% per day.
  • hydrochloric acid, 5%: mass loss 1% per day.
  • KOH 50%: mass loss 0.02% per day.
  • ammonia solution: no observed mass loss.
  • sulfate solution: shrinkage 0.02% at 28 days.
  • alkali-aggregate reaction: no expansion after 250 days (−0.01%), as shown in the figure, comparison with Portland cement (ASTM C227). These results were published in 1993. Geopolymer binders and cements even with alkali contents as high as 10%, do not generate any dangerous alkali-aggregate reaction when used with an aggregate of normal reactivity.

The need for standards

In June 2012, the institution ASTM International (former American Society for Testing and Materials, ASTM) organized a symposium on Geopolymer Binder Systems. The introduction to the symposium states: When performance specifications for Portland cement were written, non-portland binders were uncommon...New binders such as geopolymers are being increasingly researched, marketed as specialty products, and explored for use in structural concrete. This symposium is intended to provide an opportunity for ASTM to consider whether the existing cement standards provide, on the one hand, an effective framework for further exploration of geopolymer binders and, on the other hand, reliable protection for users of these materials.

The existing Portland cement standards are not adapted to geopolymer cements. They must be created by an ad hoc committee. Yet, to do so, requires also the presence of standard geopolymer cements. Presently, every expert is presenting his own recipe based on local raw materials (wastes, by-products or extracted). There is a need for selecting the right geopolymer cement category. The 2012 State of the Geopolymer R&D, suggested to select two categories, namely:

  • Type 2 slag/fly ash-based geopolymer cement: fly ashes are available in the major emerging countries;
and
  • Ferro-sialate-based geopolymer cement: this geological iron rich raw material is present in all countries throughout the globe.
and
  • the appropriate user-friendly geopolymeric reagent.

File manager

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/File_manager

A file manager or file browser is a computer program that provides a user interface to manage files and folders. The most common operations performed on files or groups of files include creating, opening (e.g. viewing, playing, editing or printing), renaming, copying, moving, deleting and searching for files, as well as modifying file attributes, properties and file permissions. Folders and files may be displayed in a hierarchical tree based on their directory structure.

Features

File transfer

Graphical file managers may support copying and moving of files through "copy and paste" and "cut and paste" respectively, as well as through drag and drop, and a separate menu for selecting the target path.

While transferring files, a file manager may show the source and destination direcotires, transfer progress in percentage and/or size, progress bar, name of the file currently being transferred, remaining and/or total number of files, numerical transfer rate, and graphical transfer rate. The ability to pause the file transfer allows temporarily granting other software full sequential read access while allowing to resume later without having to restart the file transfer.

Some file managers move multiple files by copying and deleting each selected file from the source individually, while others first copy all selected files, then delete them from the source afterwards, as described in computer file § Moving methods.

Conflicting file names in a target directory may be handled through renaming, overwriting, or skipping. Renaming is typically numerical. Overwriting may be conditional, such as when the source file is newer or differs in size. Files could technically be compared with checksums, but that would require reading through the entire source and target files, which would slow down the process significantly on larger files.

User interface

Some file managers contain features analogous to web browsers, including forward and back navigational buttons, an address bar, tabs, and a bookmark side bar.

Networking

Some file managers provide network connectivity via protocols, such as FTP, HTTP, NFS, SMB or WebDAV. This is achieved by allowing the user to browse for a file server (connecting and accessing the server's file system like a local file system) or by providing its own full client implementations for file server protocols.

Directory editors

A term that predates the usage of file manager is directory editor. An early directory editor, DIRED, was developed circa 1974 at the Stanford Artificial Intelligence Laboratory by Stan Kugell.

A directory editor was written for EXEC 8 at the University of Maryland, and was available to other users at that time. The term was used by other developers, including Jay Lepreau, who wrote the dired program in 1980, which ran on BSD. This was in turn inspired by an older program with the same name running on TOPS-20. Dired inspired other programs, including dired, the editor script (for emacs and similar editors), and ded

File-list file manager

The Alto Neptune file manager program

File-list file managers are lesser known and older than orthodox file managers.

One such file manager was neptune. It ran on the Xerox Alto in the 1973-1974 time frame. It had some of the same features that would end up in orthodox file managers.

Another such file manager is flist, which was introduced sometime before 1980 on the Conversational Monitor System. This is a variant of FULIST, which originated before late 1978, according to comments by its author, Theo Alkema.

The flist program provided a list of files in the user's minidisk, and allowed sorting by any file attribute. The file attributes could be passed to scripts or function-key definitions, making it simple to use flist as part of CMS EXEC, EXEC 2 or XEDIT scripts.

This program ran only on IBM VM/SP CMS, but was the inspiration for other programs, including filelist (a script run via the Xedit editor), and programs running on other operating systems, including a program also called flist, which ran on OpenVMS, and FULIST (from the name of the corresponding internal IBM program), which runs on Unix.

Orthodox file managers

Midnight Commander, an orthodox file manager with a text-based user interface

Orthodox file managers (sometimes abbreviated to "OFM") or command-based file managers are text-menu based file managers, that commonly have three windows (two panels and one command line window). Orthodox file managers are one of the longest running families of file managers, preceding graphical user interface-based types. Developers create applications that duplicate and extend the manager that was introduced by PathMinder and John Socha's Norton Commander for DOS. The concept dates to the mid-1980s—PathMinder was released in 1984, and Norton Commander version 1.0 was released in 1986. Despite the age of this concept, file managers based on Norton Commander are actively developed, and dozens of implementations exist for DOS, Unix, and Microsoft Windows. Nikolai Bezroukov publishes his own set of criteria for an OFM standard (version 1.2 dated June 1997).

Features

An orthodox file manager typically has three windows. Two of the windows are called panels and are positioned symmetrically at the top of the screen. The third is the command line, which is essentially a minimized command (shell) window that can be expanded to full screen. Only one of the panels is active at a given time. The active panel contains the "file cursor". Panels are resizable and can be hidden. Files in the active panel serve as the source of file operations performed by the manager. For example, files can be copied or moved from the active panel to the location represented in the passive panel. This scheme is most effective for systems in which the keyboard is the primary or sole input device. The active panel shows information about the current working directory and the files that it contains. The passive (inactive) panel shows the content of the same or another directory (the default target for file operations). Users may customize the display of columns that show relevant file information. The active panel and passive panel can be switched (often by pressing the tab key).

The following features describe the class of orthodox file managers.

  • They present the user with a two-panel directory view with a command line below. Either panel may be selected to be active; the other becomes passive. The active panel becomes the working area for delete and rename operations, while the passive panel serves as a target for copy and move operations. Panels may be shrunk, exposing the terminal window hidden behind them. Normally, only the last line of the terminal window (the command line) is visible.
  • They provide close integration with an underlying OS shell via command line, using the associated terminal window that permits viewing the results of executing shell commands entered on the command line (e.g., via Ctrl-O shortcut in Norton Commander).
  • They provide the user with extensive keyboard shortcuts.
  • The file manager frees the user from having to use the mouse.
  • Users can create their own file associations and scripts that are invoked for certain file types and organize these scripts into a hierarchical tree (e.g., as a user script library or user menu).
  • Users can extend the functionality of the manager via a so-called User menu or Start menu and extensions menu.

Other common features include:

  • Information on the "active" and "passive" panels may be used for constructing commands on the command line. Examples include current file, path to left panel, path to right panel, etc.
  • They provide a built-in viewer for (at least) the most basic file types.
  • They have a built-in editor. In many cases, the editor can extract certain elements of the panels into the text being edited.
  • Many support virtual file systems (VFS) such as viewing compressed archives, or working with files via an FTP connection.
  • They often have the word commander in the name, after Norton Commander.
  • Path: shows the source/destination location of the directory in use
  • Information about directory size, disk usage and disk name (usually at the bottom of the panels)
  • Panel with information about file name, extension, date and time of creation, last modification, and permissions (attributes).
  • Info panel with the number of files in directory, and the sum of the sizes of selected files.
  • Tabbed interface (usually in GUI file managers)
  • Function keys: F1–F10 have all the same functions under all orthodox file managers. Examples: F5 always copies file(s) from the active to the inactive panel, while F6 moves the file.

Tabbed panels

The introduction of tabbed panels in some file managers (for example Total Commander) made it possible to manipulate more than one active and passive directory at a time.

Portability

Orthodox file managers are among the most portable file managers. Examples are available on almost any platform, with both command-line and graphical interfaces. This is unusual among command line managers in that something purporting to be a standard for the interface is published. They are also actively supported by developers. This makes it possible to do the same work on different platforms without much relearning of the interface.

Dual-pane managers

Sometimes they are called dual-pane managers, a term that is typically used for programs such as the Windows File Explorer (see below). But they have three panes including a command line pane below (or hidden behind) two symmetric panes. Furthermore, most of these programs allow using just one of the two larger panes with the second hidden. Some also add an item to the Context Menu in Windows to "Open two Explorers, side by side".

Notable ones include:

Navigational file manager

File Manager in Windows 10, displaying the contents of partition X:
 

A navigational file manager is a newer type of file manager. Since the advent of GUIs, it has become the dominant type of file manager for desktop computers.

Typically, it has two panes, with the filesystem tree in the left pane and the contents of the current directory in the right pane. For macOS, the Miller columns view in Finder (originating in NeXTStep) is a variation on the navigational file manager theme.

The Miller Column browser from GNUstep is a type of Navigational file manager.

Concepts

  • The window displays the location currently being viewed.
  • The location being viewed (the current directory) can be changed by the user by opening directories, pressing a back button, typing a location, or using the additional pane with the navigation tree representing all or part of the filesystem.
  • Icons represent files, programs, and directories.

The interface in a navigational file manager often resembles a web browser, complete with back and forward buttons, and often reload buttons. Most also contain an address bar into which the file or directory path (or URI) can be typed.

Most navigational file managers have two panes, the left pane being a tree view of the filesystem. This means that unlike orthodox file managers, the two panes are asymmetrical in their content and use.

Selecting a directory in the Navigation pane on the left designates it as the current directory, displaying its contents in the Contents pane on the right. However, expanding (+) or collapsing (-) a portion of the tree without selecting a directory will not alter the contents of the right pane. The exception to this behavior applies when collapsing a parent of the current directory, in which case the selection is refocused on the collapsed parent directory, thus altering the list in the Contents pane.

The process of moving from one location to another need not open a new window. Several instances of the file manager can be opened simultaneously and communicate with each other via drag-and-drop and clipboard operations, so it is possible to view several directories simultaneously and perform cut-and paste operations between instances.

File operations are based on drag-and-drop and editor metaphors: users can select and copy files or directories onto the clipboard and then paste them in a different place in the filesystem or even in a different instance of the file manager.

Notable examples of navigational file managers include:

Spatial file manager

The Nautilus file manager had a spatial mode, which was removed with the arrival of GNOME (and with it Nautilus) version 3.x. Each of these windows displays an open directory.

Spatial file managers use a spatial metaphor to represent files and directories as if they were actual physical objects. A spatial file manager imitates the way people interact with physical objects.

Some ideas behind the concept of a spatial file manager are:

  1. A single window represents each opened directory
  2. Each window is unambiguously and irrevocably tied to a particular directory.
  3. Stability: files, directories, and windows go where the user moves them, stay where the user puts them ("preserve their spatial state"), and retain all their other "physical" characteristics (such as size, shape, color and location).
  4. The same item can only be viewed in one window at a time.

As in navigational file managers, when a directory is opened, the icon representing the directory changes—perhaps from an image showing a closed drawer to an opened one, perhaps the directory's icon turns into a silhouette filled with a pattern—and a new window is opened to represent that directory.

Examples of file managers that use a spatial metaphor to some extent include:

Dysfunctional spatial file managers:

  • Windows Explorer in Windows 95 was set as a spatial file manager model by default; because it also worked as a navigational file manager, directories could be opened in multiple windows, which made it fail all the above criteria. Later versions gradually abandoned the spatial model.
  • Apple's Finder in macOS was designed with a similar integration of spatial and navigational modes, meaning that the spatial mode did not actually work.

3D file managers

File System Visualizer, one example of a 3D file manager
 
In Cubix, files sharing the same attributes are represented by cubes in a 3D environment.

Some projects have attempted to implement a three-dimensional method of displaying files and directory structures. Three-dimensional file browsing has not become popular; the exact implementation tends to differ between projects, and there are no common standards to follow.

Examples of three-dimensional file managers include:

  • fsn, for Silicon Graphics' IRIX systems, notably featured prominently in one scene from the film Jurassic Park, as a representation of Unix systems.
  • File System Visualizer, or fsv, an open-source clone of fsn for modern Unix-like systems.
  • tdfsb, an open-source 3D file browser, where one enters directories by flying into them (using WASD). Runs on Linux, FreeBSD and BeOS.
  • BumpTop, a file manager using a three-dimensional representation of a desktop with realistic physics, intended for use with a stylus and touchscreen.
  • Real Desktop, a desktop replacement with similarities to BumpTop.
  • Cubix 3D Filer is a Windows file manager which organizes files according to different attributes.
  • GopherVR, a 3D visualisation of networked Gopher resources.

Web-based file managers

Web-based file managers are typically scripts written in either PHP, Ajax, Perl, ASP or another server-side language. When installed on a local server or on a remote server, they allow files and directories located there to be managed and edited, using a web browser, without the need for FTP Access.

More advanced, and usually commercially distributed, web-based file management scripts allow the administrator of the file manager to configure secure, individual user accounts, each with individual account permissions. Authorized users have access to documents stored on the server or in their individual user directories anytime, from anywhere, via a web browser.

A web-based file manager can serve as an organization's digital repository. For example, documents, digital media, publishing layouts, and presentations can be stored, managed, and shared between customers, suppliers, and remote workers, or just internally.

Web-based file managers are becoming increasingly popular due to the rise in popularity of dynamic web content management systems (CMS) and the need for non-technical website moderators to manage media on their websites powered by these platforms.

An example is net2ftp, a PHP- and JavaScript-based FTP client.

File picker

Operating systems typically ship a file picker, which allows specifying in which location to save a file (usually accessed through the "Save as" option in software), and where to open a file from. Sometimes, a folder is selected instead of a file or destination path.

Some file pickers also allow file management to some degree, such as searching, moving, copying, renaming, and copying the path to clipboard.

Some software might have a customized file picker.

Katyn massacre

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Katyn_massacre

Katyn massacre
Trzy krzyze.jpg
Katyn-Kharkov-Mednoye memorial in Świętokrzyskie Mountains, Poland

Katyn massacre is located in the Soviet Union
LocationKatyn Forest, Kalinin and Kharkiv prisons in Soviet Union
DateApril–May 1940
Attack type
Mass murder
Deaths22,000
VictimsPolish military officers and intelligentsia prisoners of war
PerpetratorsSoviet Union (NKVD)
Map of the sites related to the Katyn massacre
Map of the sites related to the Katyn massacre

The Katyn massacre was a series of mass executions of nearly 22,000 Polish military officers and intelligentsia prisoners of war carried out by the Soviet Union, specifically the NKVD ("People's Commissariat for Internal Affairs", the Soviet secret police) in April and May 1940. Though the killings also occurred in the Kalinin and Kharkiv prisons and elsewhere, the massacre is named after the Katyn Forest, where some of the mass graves were first discovered by German forces.

The massacre was initiated in NKVD chief Lavrentiy Beria's proposal to Joseph Stalin to execute all captive members of the Polish officer corps, which was secretly approved by the Soviet Politburo led by Stalin. Of the total killed, about 8,000 were officers imprisoned during the 1939 Soviet invasion of Poland, another 6,000 were police officers, and the remaining 8,000 were Polish intelligentsia the Soviets deemed to be "intelligence agents and gendarmes, spies and saboteurs, former landowners, factory owners and officials". The Polish Army officer class was representative of the multi-ethnic Polish state; the murdered included ethnic Poles, Ukrainians, Belarusians, and Jews including the chief Rabbi of the Polish Army, Baruch Steinberg.

The government of Nazi Germany announced the discovery of mass graves in the Katyn Forest in April 1943. Stalin severed diplomatic relations with the London-based Polish government-in-exile when it asked for an investigation by the International Committee of the Red Cross. After the Vistula–Oder offensive where the mass graves fell into Soviet control, the Soviet Union claimed the Nazis had killed the victims, and it continued to deny responsibility for the massacres until 1990, when it officially acknowledged and condemned the killings by the NKVD, as well as the subsequent cover-up by the Soviet government.

An investigation conducted by the office of the prosecutors general of the Soviet Union (1990–1991) and the Russian Federation (1991–2004) confirmed Soviet responsibility for the massacres, but refused to classify this action as a war crime or as an act of mass murder. The investigation was closed on the grounds that the perpetrators were dead, and since the Russian government would not classify the dead as victims of the Great Purge, formal posthumous rehabilitation was deemed inapplicable. In November 2010, the Russian State Duma approved a declaration blaming Stalin and other Soviet officials for ordering the massacre.

The falsified Soviet version of the events has become known as the "Katyn lie", a term coined in reference to the "Auschwitz lie".

Background

Invasion of Poland

Refer to Caption
Soviet Foreign Minister Vyacheslav Molotov signs the Molotov–Ribbentrop Pact. Behind him: 
Ribbentrop and Stalin.

On 1 September 1939, the invasion of Poland by Nazi Germany began. Consequently, Britain and France, fulfilling the Anglo-Polish and Franco-Polish treaties of alliance, declared war on Germany. Despite these declarations of war, the two nations undertook minimal military activity during what became known as the Phoney War.

The Soviet invasion of Poland began on 17 September, in accordance with the Molotov–Ribbentrop Pact. The Red Army advanced quickly and met little resistance, as Polish forces facing them were under orders not to engage the Soviets. About 250,000 to 454,700 Polish soldiers and policemen were captured and interned by the Soviet authorities. Some were freed or escaped quickly, but 125,000 were imprisoned in camps run by the NKVD. Of these, 42,400 soldiers, mostly of Ukrainian and Belarusian ethnicity serving in the Polish Army, who lived in the territories of Poland annexed by the Soviet Union, were released in October. The 43,000 soldiers born in western Poland, then under Nazi control, were transferred to the Germans; in turn, the Soviets received 13,575 Polish prisoners from the Germans.

Polish prisoners of war

Soviet repressions of Polish citizens occurred as well over this period. Since Poland's conscription system required every nonexempt university graduate to become a military reserve officer, the NKVD was able to round up a significant portion of the Polish educated class as prisoners of war. According to estimates by the Institute of National Remembrance (IPN), roughly 320,000 Polish citizens were deported to the Soviet Union (this figure is questioned by some other historians, who hold to older estimates of about 700,000–1,000,000). IPN estimates the number of Polish citizens who died under Soviet rule during World War II at 150,000 (a revision of older estimates of up to 500,000). Of the group of 12,000 Poles sent to Dalstroy camp (near Kolyma) in 1940–1941, mostly POWs, only 583 men survived; they were released in 1942 to join the Polish Armed Forces in the East. According to Tadeusz Piotrowski, "during the war and after 1944, 570,387 Polish citizens had been subjected to some form of Soviet political repression". As early as 19 September, the head of the NKVD, Lavrentiy Beria, ordered the secret police to create the Main Administration for Affairs of Prisoners of War and Internees to manage Polish prisoners. The NKVD took custody of Polish prisoners from the Red Army, and proceeded to organise a network of reception centres and transit camps, and to arrange rail transport to prisoner-of-war camps in the western USSR. The largest camps were at Kozelsk (Optina Monastery), Ostashkov (Stolobny Island on Lake Seliger near Ostashkov), and Starobelsk. Other camps were at Jukhnovo (rail station Babynino), Yuzhe (Talitsy), rail station Tyotkino (90 kilometres (56 mi) from Putyvl), Kozelshchyna, Oranki, Vologda (rail station Zaonikeevo), and Gryazovets.

A large group of Polish Prisoners of War
Polish POWs captured by the Red Army during the Soviet invasion of Poland

Kozelsk and Starobelsk were used mainly for military officers, while Ostashkov was used mainly for Polish Scouting, gendarmes, police officers, and prison officers. Some prisoners were members of other groups of Polish intelligentsia, such as priests, landowners, and law personnel. The approximate distribution of men throughout the camps was as follows: Kozelsk, 5000; Ostashkov, 6570; and Starobelsk, 4000. They totalled 15,570 men.

According to a report from 19 November 1939, the NKVD had about 40,000 Polish POWs: 8,000–8,500 officers and warrant officers, 6,000–6,500 officers of police, and 25,000 soldiers and non-commissioned officers who were still being held as POWs. In December, a wave of arrests resulted in the imprisonment of additional Polish officers. Ivan Serov reported to Lavrentiy Beria on 3 December that "in all, 1,057 former officers of the Polish Army had been arrested". The 25,000 soldiers and non-commissioned officers were assigned to forced labor (road construction, heavy metallurgy).

Preparations

Once at the camps, from October 1939 to February 1940, the Poles were subjected to lengthy interrogations and constant political agitation by NKVD officers, such as Vasily Zarubin. The prisoners assumed they would be released soon, but the interviews were in effect a selection process to determine who would live and who would die. According to NKVD reports, if a prisoner could not be induced to adopt a pro-Soviet attitude, he was declared a "hardened and uncompromising enemy of Soviet authority".

On 5 March 1940, pursuant to a note to Joseph Stalin from Beria, six members of the Soviet PolitburoStalin, Vyacheslav Molotov, Lazar Kaganovich, Kliment Voroshilov, Anastas Mikoyan, and Mikhail Kalinin — signed an order to execute 25,700 Polish "nationalists and counterrevolutionaries" kept at camps and prisons in occupied western Ukraine and Belarus. The reason for the massacre, according to the historian Gerhard Weinberg, was that Stalin wanted to deprive a potential future Polish military of a large portion of its talent. The Soviet leadership, and Stalin in particular, viewed the Polish prisoners as a "problem" as they might resist being under Soviet rule. Therefore, they decided the prisoners inside the "special camps" were to be shot as "avowed enemies of Soviet authority".

Executions

Letter in Cyrillic, dated March 5, 1940, contents per caption
Memo from Beria to Stalin, proposing the execution of Polish officers

The number of victims is estimated at 22,000, with a lower limit of confirmed dead of 21,768. According to Soviet documents declassified in 1990, 21,857 Polish internees and prisoners were executed after 3 April 1940: 14,552 prisoners of war (most or all of them from the three camps) and 7,305 prisoners in western parts of the Byelorussian and Ukrainian SSRs. Of them 4,421 were from Kozelsk, 3,820 from Starobelsk, 6,311 from Ostashkov, and 7,305 from Byelorussian and Ukrainian prisons. The head of the NKVD Administration for Affairs of Prisoners of War and Internees, Pyotr Soprunenko [ru], was involved in "selections" of Polish officers to be executed at Katyn and elsewhere.

Those who died at Katyn included soldiers (an admiral, two generals, 24 colonels, 79 lieutenant colonels, 258 majors, 654 captains, 17 naval captains, 85 privates, 3,420 non-commissioned officers, and seven chaplains), 200 pilots, government representatives and royalty (a prince, 43 officials), and civilians (three landowners, 131 refugees, 20 university professors, 300 physicians; several hundred lawyers, engineers, and teachers; and more than 100 writers and journalists). In all, the NKVD executed almost half the Polish officer corps. Altogether, during the massacre, the NKVD executed 14 Polish generals: Leon Billewicz (ret.), Bronisław Bohatyrewicz (ret.), Xawery Czernicki (admiral), Stanisław Haller (ret.), Aleksander Kowalewski [pl], Henryk Minkiewicz (ret.), Kazimierz Orlik-Łukoski, Konstanty Plisowski (ret.), Rudolf Prich (killed in Lviv), Franciszek Sikorski (ret.), Leonard Skierski (ret.), Piotr Skuratowicz, Mieczysław Smorawiński, and Alojzy Wir-Konas (promoted posthumously). Not all of the executed were ethnic Poles, because the Second Polish Republic was a multiethnic state, and its officer corps included Belarusians, Ukrainians, and Jews. It is estimated about 8% of the Katyn massacre victims were Polish Jews. 395 prisoners were spared from the slaughter, among them Stanisław Swianiewicz and Józef Czapski. They were taken to the Yukhnov camp or Pavlishtchev Bor and then to Gryazovets. Up to 99% of the remaining prisoners were killed. People from the Kozelsk camp were executed in Katyn Forest; people from the Starobelsk camp were killed in the inner NKVD prison of Kharkiv and the bodies were buried near the village of Piatykhatky; and police officers from the Ostashkov camp were killed in the internal NKVD prison of Kalinin (Tver) and buried in Mednoye. All three burial sites had already been secret cemeteries of the victims of the Great Purge of 1937–1938. Later, recreational areas of NKVD/KGB were established there.

Aerial view of the Katyn massacre grave
 
Photo from 1943 exhumation of mass grave of Polish officers killed by NKVD in Katyń Forest
 
A mass grave, with multiple corpses visible
A mass grave at Katyn, 1943

Detailed information on the executions in the Kalinin NKVD prison was provided during a hearing by Dmitry Tokarev, former head of the Board of the District NKVD in Kalinin. According to Tokarev, the shooting started in the evening and ended at dawn. The first transport, on 4 April 1940, carried 390 people, and the executioners had difficulty killing so many people in one night. The following transports held no more than 250 people. The executions were usually performed with German-made .25 ACP Walther Model 2 pistols supplied by Moscow, but Soviet-made 7.62×38mmR Nagant M1895 revolvers were also used. The executioners used German weapons rather than the standard Soviet revolvers, as the latter were said to offer too much recoil, which made shooting painful after the first dozen executions. Vasily Mikhailovich Blokhin, chief executioner for the NKVD, is reported to have personally shot and killed 7,000 of the condemned, some as young as 18, from the Ostashkov camp at Kalinin prison, over 28 days in April 1940.

After the condemned individual's personal information was checked and approved, he was handcuffed and led to a cell insulated with stacks of sandbags along the walls, and a heavy, felt-lined door. The victim was told to kneel in the middle of the cell, and was then approached from behind by the executioner and immediately shot in the back of the head or neck. The body was carried out through the opposite door and laid in one of the five or six waiting trucks, whereupon the next condemned was taken inside and subjected to the same treatment. In addition to muffling by the rough insulation in the execution cell, the pistol gunshots were masked by the operation of loud machines (perhaps fans) throughout the night. Some post-1991 revelations suggest prisoners were also executed in the same manner at the NKVD headquarters in Smolensk, though judging by the way the corpses were stacked, some captives may have been shot while standing on the edge of the mass graves. This procedure went on every night, except for the public May Day holiday.

Some 3,000 to 4,000 Polish inmates of Ukrainian prisons and those from Belarus prisons were probably buried in Bykivnia and in Kurapaty respectively, about 50 women including two sisters, Klara Auerbach-Margules and Stella Menkes, among them. Lieutenant Janina Lewandowska, daughter of Gen. Józef Dowbor-Muśnicki, was the only woman POW executed during the massacre at Katyn.

Discovery

17 men, most in military uniform, stand in a cemetery, inspecting two graves.
Secretary of State of the Vichy regime Fernand de Brinon and others in Katyn at the graves of Mieczysław Smorawiński and Bronisław Bohatyrewicz, April 1943

The question about the fate of the Polish prisoners was raised soon after Operation Barbarossa began in June 1941. The Polish government-in-exile and the Soviet government signed the Sikorski–Mayski agreement, which announced the willingness of both to fight together against Nazi Germany and for a Polish army to be formed on Soviet territory. The Polish general Władysław Anders began organizing this army, and soon he requested information about the missing Polish officers. During a personal meeting, Stalin assured him and Władysław Sikorski, the Polish Prime Minister, all the Poles were freed, and not all could be accounted because the Soviets "lost track" of them in Manchuria. Józef Czapski investigated the fate of Polish officers between 1941 and 1942.

In 1942, with the territory around Smolensk under German occupation, captive Polish railroad workers heard from the locals about a mass grave of Polish soldiers at Kozelsk near Katyn; finding one of the graves, they reported it to the Polish Underground State. The discovery was not seen as important, as nobody thought the discovered grave could contain so many victims. In early 1943, Rudolf Christoph Freiherr von Gersdorff, a German officer serving as the intelligence liaison between the Wehrmacht's Army Group Centre and Abwehr, received reports about mass graves of Polish military officers. These reports stated the graves were in the forest of Goat Hill near Katyn. He passed the reports to his superiors (sources vary on when exactly the Germans became aware of the graves—from "late 1942" to January–February 1943, and when the German top decision makers in Berlin received those reports [as early as 1 March or as late as 4 April]). Joseph Goebbels saw this discovery as an excellent tool to drive a wedge between Poland, the Western Allies, and the Soviet Union, and reinforcement for the Nazi propaganda line about the horrors of Bolshevism, and American and British subservience to it. After extensive preparation, on 13 April, Reichssender Berlin broadcast to the world that German military forces in the Katyn forest near Smolensk had uncovered a ditch that was "28 metres long and 16 metres wide [92 ft by 52 ft], in which the bodies of 3,000 Polish officers were piled up in 12 layers". The broadcast went on to charge the Soviets with carrying out the massacre in 1940.

Refer to caption
Polish banknotes and epaulets recovered from mass graves

The Germans brought in a European Red Cross committee called the Katyn Commission, comprising 12 forensic experts and their staff, from Belgium, Bulgaria, Croatia, Denmark, Finland, France, Hungary, Italy, the Netherlands, Romania, Switzerland, and Bohemia & Moravia. The Germans were so intent on proving the Soviets were behind the massacre they even included some Allied prisoners of war, among them writer Ferdynand Goetel, the Polish Home Army prisoner from Pawiak. After the war, Goetel escaped with a fake passport due to an arrest warrant issued against him. Jan Emil Skiwski was a collaborator. Józef Mackiewicz has published several texts about the crime. Two of the 12, the Bulgarian Marko Markov and the Czech František Hájek, with their countries becoming satellite states of the Soviet Union, were forced to recant their evidence, defending the Soviets and blaming the Germans. The Croatian pathologist Eduard Miloslavić managed to escape to the US. The Katyn massacre was beneficial to Nazi Germany, which used it to discredit the Soviet Union. On 14 April 1943, Goebbels wrote in his diary: "We are now using the discovery of 12,000 Polish officers, killed by the GPU, for anti-Bolshevik propaganda on a grand style. We sent neutral journalists and Polish intellectuals to the spot where they were found. Their reports now reaching us from ahead are gruesome. The Führer has also given permission for us to hand out a drastic news item to the German press. I gave instructions to make the widest possible use of the propaganda material. We shall be able to live on it for a couple of weeks".

The decomposing remains of Katyn victims, found in a mass grave.
Katyn exhumation, 1943

The Soviet government immediately denied the German charges. They claimed the Polish prisoners of war had been engaged in construction work west of Smolensk, and consequently were captured and executed by invading German units in August 1941. The Soviet response on 15 April to the initial German broadcast of 13 April, prepared by the Soviet Information Bureau, stated "Polish prisoners-of-war who in 1941 were engaged in construction work west of Smolensk and who...fell into the hands of the German-Fascist hangmen". In April 1943, the Polish government-in-exile led by Sikorski insisted on bringing the matter to the negotiation table with the Soviets and on opening an investigation by the International Red Cross. Stalin, in response, accused the Polish government of collaborating with Nazi Germany and broke off diplomatic relations with it. The Soviet Union also started a campaign to get the Western Allies to recognize the pro-Soviet government-in-exile of the Union of Polish Patriots led by Wanda Wasilewska. Sikorski died in the 1943 Gibraltar B-24 crash —an event convenient for the Allied leaders.

Soviet actions

When Joseph Goebbels was informed in September 1943 that the German Army had to withdraw from the Katyn area, he wrote a prediction in his diary. His entry for 29 September 1943 reads: "Unfortunately, we have had to give up Katyn. The Bolsheviks undoubtedly will soon 'find' that we shot 12,000 Polish officers. That episode is one that is going to cause us quite a little trouble in the future. The Soviets are undoubtedly going to make it their business to discover as many mass-graves as possible and then blame it on us".

Having retaken the Katyn area almost immediately after the Red Army had recaptured Smolensk, around September–October 1943, NKVD forces began a cover-up operation. They destroyed a cemetery the Germans had permitted the Polish Red Cross to build and removed other evidence. Witnesses were "interviewed" and threatened with arrest for collaborating with the Nazis if their testimonies disagreed with the official line. As none of the documents found on the dead had dates later than April 1940, the Soviet secret police planted false evidence to place the apparent time of the massacre in mid-1941, when the German military had controlled the area. NKVD operatives Vsevolod Merkulov and Sergei Kruglov issued a preliminary report, dated 10–11 January 1944, that concluded the Polish officers were shot by German soldiers.

In January 1944, the Soviet Extraordinary State Commission for ascertaining and investigating crimes perpetrated by the German-Fascist invaders set up another commission, the Special Commission for Determination and Investigation of the Shooting of Polish Prisoners of War by German-Fascist Invaders in Katyn Forest [pl] (Специальная комиссия по установлению и расследованию обстоятельств расстрела немецко-фашистскими захватчиками в Катынском лесу (близ Смоленска) военнопленных польских офицеров). The commission's name implied a predestined conclusion. It was headed by Nikolai Burdenko, the president of the USSR Academy of Medical Sciences, hence the commission is often known as the "Burdenko Commission", who was appointed by Moscow to investigate the incident. Its members included prominent Soviet figures such as the writer Aleksey Nikolayevich Tolstoy, but no foreign personnel were allowed to join the commission. The Burdenko Commission exhumed the bodies, rejected the 1943 German findings the Poles were shot by the Soviet army, assigned the guilt to the Nazis, and concluded all the shootings were done by German occupation forces in late 1941. It is uncertain how many members of the commission were misled by the falsified reports and evidence, and how many actually suspected the truth. Cienciala and Materski note the commission had no choice but to issue findings in line with the Merkulov-Kruglov report, and Burdenko was likely aware of the cover-up. He reportedly admitted something like that to friends and family shortly before his death in 1946. The Burdenko Commission's conclusions would be consistently cited by Soviet sources until the official admission of guilt by the Soviet government on 13 April 1990.

In January 1944, the Soviets also invited a group of more than a dozen mostly American and British journalists, accompanied by Kathleen Harriman, the daughter of the new American Ambassador W. Averell Harriman, and John F. Melby, third secretary at the American embassy in Moscow, to Katyn. Some regarded the inclusion of Melby and Harriman as a Soviet attempt to lend official weight to their propaganda. Melby's report noted the deficiencies in the Soviet case: problematic witnesses; attempts to discourage questioning of the witnesses; statements of the witnesses obviously being given as a result of rote memorization; and that "the show was put on for the benefit of the correspondents." Nevertheless, Melby, at the time, felt on balance the Soviet case was convincing. Harriman's report reached the same conclusion and after the war both were asked to explain why their conclusions seemed to be at odds with their findings, with the suspicion the conclusions were what the State Department wanted to hear. The journalists were less impressed and not convinced by the staged Soviet demonstration.

An example of Soviet propaganda spread by some Western Communists is Alter Brody's monograph Behind the Polish-Soviet Break (with an introduction by Corliss Lamont).

Western response

Eight soldiers in World War II-era uniforms, as per caption
British, Canadian, and American officers (POWs) brought by the Germans to view the exhumations

The growing Polish-Soviet tension was beginning to strain Western-Soviet relations at a time when the Poles' importance to the Allies, significant in the first years of the war, was beginning to fade, due to the entry into the conflict of the military and industrial giants, the Soviet Union and the United States. In retrospective review of records, both British Prime Minister Winston Churchill and U.S. President Franklin D. Roosevelt were increasingly torn between their commitments to their Polish ally and the demands by Stalin and his diplomats.

According to the Polish diplomat Edward Bernard Raczyński, Raczyński and General Sikorski met privately with Churchill and Alexander Cadogan on 15 April 1943, and told them the Poles had proof the Soviets were responsible for the massacre. Raczyński reports Churchill, "without committing himself, showed by his manner that he had no doubt of it". Churchill said "The Bolsheviks can be very cruel". On 17 April 1943 the Polish government issued a statement on this issue, asking for a Red Cross investigation, which was rejected by Stalin, who used the fact that Germans also requested such an investigation as a "proof" of Polish-German conspiracy, and which led to a deterioration of Polish-Soviet relations. Shortly afterward, however, on 24 April 1943, the British government successfully pressured the Poles to withdraw the request for a Red Cross investigation, and Churchill assured Stalin's regime: "We shall certainly oppose vigorously any 'investigation' by the International Red Cross or any other body in any territory under German authority. Such an investigation would be a fraud and its conclusions reached by terrorism". Unofficial or classified UK documents concluded Soviet guilt was a "near certainty", but the alliance with the Soviets was deemed to be more important than moral issues; thus the official version supported the Soviets, up to censoring any contradictory accounts. Churchill asked Owen O'Malley to investigate the issue, but in a note to the Foreign Secretary he noted: "All this is merely to ascertain the facts, because we should none of us ever speak a word about it." O'Malley pointed out several inconsistencies and near impossibilities in the Soviet version. Later, Churchill sent a copy of the report to Roosevelt on 13 August 1943. The report deconstructed the Soviet account of the massacre and alluded to the political consequences within a strongly moral framework but recognized there was no viable alternative to the existing policy. No comment by Roosevelt on the O'Malley report has been found. Churchill's own post-war account of the Katyn affair gives little further insight. In his memoirs, he refers to the 1944 Soviet inquiry into the massacre, which found the Germans responsible, and adds, "belief seems an act of faith".

Lt. Col. John H. Van Vliet Jr communication on Katyn

At the beginning of 1944, Ron Jeffery, an agent of British and Polish intelligence in occupied Poland, eluded the Abwehr and travelled to London with a report from Poland to the British government. His efforts were at first highly regarded, but subsequently ignored, which a disillusioned Jeffery later attributed to the actions of Kim Philby and other high-ranking communist agents entrenched in the British government. Jeffery tried to inform the British government about the Katyn massacre, but was as a result released from the Army.

In 1947, the Polish Government in exile 1944–1946 report on Katyn was transmitted to Telford Taylor.

In the United States a similar line was taken, notwithstanding two official intelligence reports into the Katyn massacre that contradicted the official position. In 1944, Roosevelt assigned his special emissary to the Balkans, Navy Lieutenant Commander George Earle, to produce a report on Katyn. Earle concluded the massacre was committed by the Soviet Union. Having consulted with Elmer Davis, director of the United States Office of War Information, Roosevelt rejected the conclusion (officially), declared he was convinced of Nazi Germany's responsibility, and ordered that Earle's report be suppressed. When Earle requested permission to publish his findings, the President issued a written order to desist. Earle was reassigned and spent the rest of the war in American Samoa.

A further report in 1945, supporting the same conclusion, was produced and stifled. In 1943, the Germans took two U.S. POWs—Capt. Donald B. Stewart and Col. John H. Van Vliet [de]—to Katyn for an international news conference. Documents released by the National Archives and Records Administration in September 2012 revealed Stewart and Van Vliet sent coded messages to their American superiors indicating they saw proof that implicated the Soviets. Three lines of evidence were cited. Firstly, the Polish corpses were in such an advanced state of decay that the Nazis could not have killed them, as they had only taken over the area in 1941. Secondly, none of the numerous Polish artifacts, such as letters, diaries, photographs and identification tags pulled from the graves, were dated later than the spring of 1940. Most incriminating was the relatively good state of the men's uniforms and boots, which showed they had not lived long after being captured. Later, in 1945, Van Vliet submitted a report concluding the Soviets were responsible for the massacre. His superior, Major General Clayton Lawrence Bissell, General George Marshall's assistant chief of staff for intelligence, destroyed the report. Washington kept the information secret, presumably to appease Stalin and not distract from the war against the Nazis. During the 1951–52 Congressional investigation into Katyn, Bissell defended his action before the United States Congress, arguing it was not in the U.S. interest to antagonize an ally (the USSR) whose assistance the nation needed against the Empire of Japan. In 1950, Van Vliet recreated his wartime report. In 2014, a copy of a report Van Vliet made in France during 1945 was discovered.

Post-war trials

From 28 December 1945 to 4 January 1946, a Soviet military court in Leningrad tried seven Wehrmacht servicemen. One of them, Arno Dürre, who was charged with murdering numerous civilians using machine-guns in Soviet villages, confessed to having taken part in the burial (though not the execution) of 15,000 to 20,000 Polish POWs in Katyn. For this he was spared execution and was given 15 years of hard labor. His confession was full of absurdities, and thus he was not used as a Soviet prosecution witness during the Nuremberg trials. He later recanted his confession, claiming the investigators forced him to confess.

At the London conference that drew up the indictments of German war crimes before the Nuremberg trials, the Soviet negotiators put forward the allegation, "In September 1941, 925 Polish officers who were prisoners of war were killed in the Katyn Forest near Smolensk". The U.S. negotiators agreed to include it, but were "embarrassed" by the inclusion (noting the allegation had been debated extensively in the press) and concluded it would be up to the Soviets to sustain it. At the trials in 1946, Soviet General Roman Rudenko raised the indictment, stating "one of the most important criminal acts for which the major war criminals are responsible was the mass execution of Polish prisoners of war shot in the Katyn forest near Smolensk by the German fascist invaders", but failed to make the case and the U.S. and British judges dismissed the charges. Only 70 years later did it become known that former OSS chief William Donovan had succeeded in getting the American delegation in Nuremberg to block the Katyn indictment. A German officer, Fabian von Schlabrendorff, who was stationed in Smolensk during the war, had convinced Donovan that not the Germans but the Soviets were the perpetrators. It was not the purpose of the court to determine whether Germany or the Soviet Union was responsible for the crime, but rather to attribute the crime to at least one of the defendants, which the court was unable to do.

1950s

In 1951 and 1952, with the Korean War as a background, a congressional investigation chaired by Rep. Ray Madden and known as the Madden Committee investigated the Katyn massacre. According to the Committee conclusion: "the Katyn massacre involved some 4,243 of the 15,400 Polish Army officers and intellectual leaders who were captured by the Soviets when Russia invaded Poland in September 1939." The committee concluded that these 4,243 Poles had been killed by the NKVD and that a case should be brought to the International Court of Justice. However, the question of responsibility remained controversial in the West as well as behind the Iron Curtain. In the United Kingdom in the late 1970s, plans for a memorial to the victims bearing the date 1940 (rather than 1941) were condemned as provocative in the political climate of the Cold War. It has also been alleged that the choice made in 1969 for the location of the Byelorussian Soviet Socialist Republic war memorial at the former Belarusian village named Khatyn, the site of the 1943 Khatyn massacre, was made to cause confusion with Katyn. The two names are similar or identical in many languages, and were often confused.

In Poland, the pro-Soviet authorities following the Soviet occupation after the war covered up the matter in accordance with the official Soviet propaganda line, deliberately censoring any sources that might provide information about the crime. Katyn was a forbidden topic in post-war Poland. Censorship in the Polish People's Republic was a massive undertaking and Katyn was specifically mentioned in the "Black Book of Censorship" used by the authorities to control the media and academia. Not only did government censorship suppress all references to it, but even mentioning the atrocity was dangerous. In the late 1970s, democracy groups like the Workers' Defence Committee and the Flying University defied the censorship and discussed the massacre, in the face of arrests, beatings, detentions, and ostracism. In 1981, Polish trade union Solidarity erected a memorial with the simple inscription "Katyn, 1940". It was confiscated by the police and replaced with an official monument with the inscription: "To the Polish soldiers—victims of Hitlerite fascism—reposing in the soil of Katyn". Nevertheless, every year on the day of Zaduszki, similar memorial crosses were erected at Powązki Cemetery and numerous other places in Poland, only to be dismantled by the police. Katyn remained a political taboo in the Polish People's Republic until the fall of the Eastern Bloc in 1989.

In the Soviet Union during the 1950s, the head of KGB, Alexander Shelepin, proposed and carried out the destruction of many documents related to the Katyn massacre to minimize the chance the truth would be revealed. His 3 March 1959 note to Nikita Khrushchev, with information about the execution of 21,857 Poles and with the proposal to destroy their personal files, became one of the documents that was preserved and eventually made public.

Revelations

A low stone wall, curving upward. Three statues of Polish soldiers are mounted at its center. Below the statues, Text is mounted as per caption.
Monument in Katowice, Poland, memorializing "Katyn, Kharkiv, Mednoye and other places of killing in the former USSR in 1940"

During the 1980s, there was increasing pressure on both the Polish and Soviet governments to release documents related to the massacre. Polish academics tried to include Katyn in the agenda of the 1987 joint Polish-Soviet commission to investigate censored episodes of the Polish-Russian history. In 1989, Soviet scholars revealed Joseph Stalin had indeed ordered the massacre, and in 1990 Mikhail Gorbachev admitted the NKVD had executed the Poles and confirmed two other burial sites similar to the site at Katyn: Mednoye and Piatykhatky.

On 30 October 1989, Gorbachev allowed a delegation of several hundred Poles, organized by the Polish association Families of Katyń Victims, to visit the Katyn memorial. This group included former U.S. national security advisor Zbigniew Brzezinski. A mass was held and banners hailing the Solidarity movement were laid. One mourner affixed a sign reading "NKVD" on the memorial, covering the word "Nazis" in the inscription such that it read "In memory of Polish officers killed by the NKVD in 1941." Several visitors scaled the fence of a nearby KGB compound and left burning candles on the grounds. Brzezinski commented:

It isn't a personal pain which has brought me here, as is the case in the majority of these people, but rather recognition of the symbolic nature of Katyń. Russians and Poles, tortured to death, lie here together. It seems very important to me that the truth should be spoken about what took place, for only with the truth can the new Soviet leadership distance itself from the crimes of Stalin and the NKVD. Only the truth can serve as the basis of true friendship between the Soviet and the Polish peoples. The truth will make a path for itself. I am convinced of this by the very fact that I was able to travel here.

His remarks were given extensive coverage on Soviet television. On 13 April 1990, the forty-seventh anniversary of the discovery of the mass graves, the USSR formally expressed "profound regret" and admitted Soviet secret police responsibility. The day was declared a worldwide Katyn Memorial Day (Polish: Światowy Dzień Pamięci Ofiar Katynia).

Post-communist investigations

In 1990, future Russian President Boris Yeltsin released the top-secret documents from the sealed "Package №1." and transferred them to the new Polish president Lech Wałęsa. Among the documents was a proposal by Lavrentiy Beria, dated 5 March 1940, to execute 25,700 Poles from Kozelsk, Ostashkov and Starobelsk camps, and from certain prisons of Western Ukraine and Belarus, signed by Stalin (among others). Another document transferred to the Poles was Aleksandr Shelepin's 3 March 1959 note to Nikita Khrushchev, with information about the execution of 21,857 Poles, as well as a proposal to destroy their personal files to reduce the possibility documents related to the massacre would be uncovered later. The revelations were also publicized in the Russian press, where they were interpreted as being one outcome of an ongoing power struggle between Yeltsin and Gorbachev.

Criminal prosecution attempts and further testimonies

In 1991, the Chief Military Prosecutor for the Soviet Union began proceedings against Pyotr Karpovich Soprunenko (b. 1908) for his role in the Katyn killings, but eventually declined to prosecute because Soprunenko was 83, almost blind, and recovering from a cancer operation. During his April 1991 interrogation, Soprunenko defended himself by denying his own signature. Soprunenko, who died in June 1992, was an NKVD captain in early 1940 and was the organization's Head of Directorate for Prisoners of War Affairs & Internees, from September 1939 to February 1943. In this capacity, he was reportedly involved in the planning and operational control of the executions, in following with Beria's and Merkulov's orders.

Further testimonies emerged in October 1991 via a report made by Nicholas Bethell, a British historian and Conservative member of the European Parliament, who obtained videotaped copies of the interrogations to surviving participants, statements, and met with military prosecutors in Moscow. His report mentioned Soprunenko and another participant, Vladimir Tokaryev, who was 89 but still recalled how 250 Poles were murdered every night in Kalinin. Bethell's report, which was published in The Observer, also quoted Tokaryev as saying that he learned of the massacre's plan in March 1940; he was called to a meeting in Moscow with Bogdan Kobulov, Beria's NKVD deputy, and claimed that Soprunenko was present in said meeting, in which the latter explained details of the operation. Moreover, Bethell's spoke of Soprunenko telling that he received an order from the Politburo to carry out the executions, signed by Stalin. Bethell also characterized Soprunenko as ″evasive and shifty″ in his deposition, showing little regret for his role.

A number of candles are arranged in a cross shape in a roadway, while a crowd of people look on.
Ceremony of military upgrading of Katyn massacre victims, Piłsudski Square, Warsaw, 10 November 2007

Later events

During Kwaśniewski's visit to Russia in September 2004, Russian officials announced they were willing to transfer all the information on the Katyn massacre to the Polish authorities as soon as it became declassified. In March 2005 the Prosecutor-General's Office of the Russian Federation concluded a decade-long investigation of the massacre and announced that the investigation was able to confirm the deaths of 1,803 out of 14,542 Polish citizens who had been sentenced to death while in three Soviet camps. He did not address the fate of about 7,000 victims who had not been in POW camps, but in prisons. Savenkov declared the massacre was not a genocide, that Soviet officials who had been found guilty of the crime were dead and that, consequently, "there is absolutely no basis to talk about this in judicial terms". Of the 183 volumes of files gathered during the Russian investigation, 116 were declared to contain state secrets and were classified.

On 22 March 2005, the Polish Sejm unanimously passed an act requesting the Russian archives to be declassified. The Sejm also requested Russia to classify the Katyn massacre as a crime of genocide. The resolution stressed that the authorities of Russia "seek to diminish the burden of this crime by refusing to acknowledge it was genocide and refuse to give access to the records of the investigation into the issue, making it difficult to determine the whole truth about the killing and its perpetrators."

In 2007, a case (Janowiec and Others v. Russia) was brought in front of the European Court of Human Rights, with the families of several victimes claiming that Russia violated the European Convention on Human Rights by withholding documents from the public. The declared admissible two complaints from relatives of the massacre victims against Russia regarding adequacy of the official investigation. In a ruling on 16 April 2012, the court found Russia had violated the rights of victims' relatives by not providing them with sufficient information about the investigation and described the massacre as a "war crime". But it also refused to judge the effectiveness of the Soviet Russian investigation because the related events took place before Russia ratified the Human Rights Convention in 1998. The plaintiffs filed an appeal but a 21 October 2013 ruling essentially reaffirmed the prior one, claiming that the matter is outside the court's competence, and only rebuking the Russian side for its failure to substantiate adequately why some critical information remained classified. In late 2007 and early 2008, several Russian newspapers, including Rossiyskaya Gazeta, Komsomolskaya Pravda, and Nezavisimaya Gazeta, printed stories that implicated the Nazis in the crime, spurring concern this was done with the tacit approval of the Kremlin. As a result, the Polish Institute of National Remembrance decided to open its own investigation.

In 2008, the Polish Foreign Ministry asked the government of Russia about alleged footage of the massacre filmed by the NKVD during the killings, something the Russians have denied exists. Polish officials believe this footage, as well as further documents showing cooperation of Soviets with the Gestapo during the operations, are the reason for Russia's decision to classify most of the documents about the massacre.

In the following years, 81 volumes of the case were declassified and transferred to the Polish government. As of 2012, 35 out of 183 volumes of files remain classified.

In June 2008, Russian courts consented to hear a case about the declassification of documents about Katyn and the judicial rehabilitation of the victims. In an interview with a Polish newspaper, Vladimir Putin called Katyn a "political crime".

In September 2009, Yevgeny Dzhugashvili, Stalin's grandson, sued Russian newspaper Novaya Gazeta after it published an article claiming his grandfather personally signed execution orders against civilians. Dzhugashvili centered his case on the veracity of a document showing Stalin ordered the Katyn massacre. On 13 October 2009, the Russian court rejected the suit.

On 21 April 2010, the Russian Supreme Court ordered the Moscow City Court to hear an appeal in an ongoing Katyn legal case. A civil rights group, Memorial, said the ruling could lead to a court decision to open up secret documents providing details about the killings of thousands of Polish officers. Russia handed over to Poland copies of 137 of the 183 volumes of unclassified material of Russian investigation of the Katyn criminal case. Russian President Dmitry Medvedev handed one of the volumes to the acting Polish president, Bronislaw Komorowski. Medvedev and Komorowski agreed the two states should continue to try to reveal the truth about the tragedy. The Russian president reiterated Russia would continue to declassify documents on the Katyn massacre and ordered to release the documents proving the guilt of Stalin and his secret police chief Beria. The acting Polish president said Russia's move might lay a good foundation for improving bilateral relations. In November 2010, the Russian State Duma issued an official declaration that condemned Joseph Stalin for Katyn massacres.

Archive searches are continuing in the Belarus state archives for the "Belarusian Katyn List" expected to contain the names of 3,870 officers whose identities and exact place of execution (presumably Bykivnia and Kuropaty, as mentioned above) were not yet established.

Legacy

Polish–Russian relations

Russian President Dmitry Medvedev and Polish President Bronislaw Komorowski laying wreaths at the Katyn massacre memorial complex, 11 April 2011

Russia and Poland remained divided on the legal description of the Katyn crime. The Poles considered it a case of genocide and demanded further investigations, as well as complete disclosure of Soviet documents.

In June 1998, Boris Yeltsin and Aleksander Kwaśniewski agreed to construct memorial complexes at Katyn and Mednoye, the two NKVD execution sites on Russian soil. In September of that year, the Russians also raised the issue of Soviet prisoner of war deaths in the camps for Russian prisoners and internees in Poland (1919–24). About 16,000 to 20,000 POWs died in those camps due to communicable diseases. Some Russian officials argued it was "a genocide comparable to Katyn". A similar claim was raised in 1994; such attempts are seen by some, particularly in Poland, as a highly provocative Russian attempt to create an "anti-Katyn" and "balance the historical equation". The fate of Polish prisoners and internees in Soviet Russia remains poorly researched.

On 4 February 2010, the Prime Minister of Russia, Vladimir Putin, invited his Polish counterpart, Donald Tusk, to attend a Katyn memorial service in April. The visit took place on 7 April 2010, when Tusk and Putin together commemorated the 70th anniversary of the massacre. Before the visit, the 2007 film Katyń was shown on Russian state television for the first time. The Moscow Times commented that the film's premiere in Russia was likely a result of Putin's intervention.

On 10 April 2010, an aircraft carrying Polish President Lech Kaczyński with his wife and 87 other politicians and high-ranking army officers crashed in Smolensk, killing all 96 aboard the aircraft. The passengers were to attend a ceremony marking the 70th anniversary of the Katyn massacre. The Polish nation was stunned; Prime Minister Donald Tusk, who was not on the plane, referred to the crash as "the most tragic Polish event since the war." In the aftermath, a number of conspiracy theories began to circulate. The catastrophe has also had major echoes in the international and particularly the Russian press, prompting a rebroadcast of Katyń on Russian television. The Polish President was to deliver a speech at the formal commemorations. The speech was to honour the victims, highlight the significance of the massacres in the context of post-war communist political history, as well as stress the need for Polish–Russian relations to focus on reconciliation. Although the speech was never delivered, it has been published with a narration in the original Polish and a translation has also been made available in English.

In November 2010, the State Duma (lower house of the Russian parliament) passed a resolution declaring long-classified documents "showed that the Katyn crime was carried out on direct orders of Stalin and other Soviet officials". The declaration also called for the massacre to be investigated further to confirm the list of victims. Members of the Duma from the Communist Party denied the Soviet Union had been to blame for the Katyn massacre and voted against the declaration. On 6 December 2010, Russian President Dmitry Medvedev expressed commitment to uncovering the whole truth about the massacre, stating "Russia has recently taken a number of unprecedented steps towards clearing up the legacy of the past. We will continue in this direction".

On 10 April 2022, in response to Polish authorities attempts to demolish or remove "post-Soviet occupation monuments", pro-government activists in support of the invasion parked heavy machinery with flags of the Russian Federation and letters Z outside the Katyn Memorial Cemetery, which was interpreted as an act of intimidation. This was denied by the organizers, who stated they wished to draw attention to the "Russophobic Polish authorities". A number of Russian politicians advocated to demolish Polish part of the memorial complex. Among them State Duma deputies Anatoly Wasserman and Alexey Chepa. On 28 June 2022 Leningradsky Court of Kaliningrad forbade distribution of the book "Katyn. On the trail of a crime". According to the court the book "rehabilitated Nazism" and "violated the law on glorifying Soviet Victory in the Great Patriotic War".

Those adopting pre-1990 views

The Communist Party of the Russian Federation and a number of other pro-Soviet Russian politicians and commentators claim that the story of Soviet guilt is a conspiracy and that the documents released in 1990 were forgeries. They insist that the original version of events, assigning guilt to the Nazis, is the correct version, and they call on the Russian government to start a new investigation that would revise the findings of 2004.

A number of Russian historians and organizations such as Memorial openly admit Soviet responsibility. In particular, they point to inconsistencies in this alternative version, namely the details of another contemporary mass execution site at Mednoye in the Tver Region. That part of Central Russia, they stress, was never under German occupation and yet it contained the remains of victims originating from the same camps as those killed in Katyn; the victims at Mednoye were also killed in April–May 1940. Mednoye was only examined in the 1990s and was found to contain well-preserved Polish uniforms, documents, souvenirs, and Soviet newspapers dating back to 1940.

In 2021, however, the Russian Ministry of Culture downgraded the memorial complex at Katyn on its Register of Sites of Cultural Heritage from a place of federal to one of only regional importance. Such decisions, says the preface to the site, are made in consultation with the regional authorities, i.e. the Smolensk Region administration. More important, the Ministry altered the descriptive text to say, once more, that the "Polish officers were shot by the Hitlerites in 1941".

In June 2022, Russia removed the Polish flag from the memorial complex, amidst a rise in Russia–Poland political tension due to the 2022 Russian invasion of Ukraine.

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