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United States Department of Defense Seal.svg
Agency overview
Formed18 September 1947; 71 years ago (as National Military Establishment)
Preceding agencies
TypeExecutive department
JurisdictionU.S. federal government
HeadquartersThe Pentagon
Arlington, Virginia, U.S.
38°52′16″N 77°3′21″WCoordinates: 38°52′16″N 77°3′21″W
Employees732,079 (civilian)
1,300,000 (active duty military)
826,000 (National Guard and reserve): 2.86 million total (2018)
Annual budget$686.1 billion (2019) - Discretionary 
Agency executives
Child agencies
Websitewww.defense.gov

The Department of Defense (DoD, USDOD, or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government concerned directly with national security and the United States Armed Forces. The department is the largest employer in the world, with nearly 1.3 million active duty servicemen and women as of 2016. Adding to its employees are over 826,000 National Guardsmen and Reservists from the four services, and over 732,000 civilians bringing the total to over 2.8 million employees. Headquartered at the Pentagon in Arlington, Virginia, just outside Washington, D.C., the DoD's stated mission is to provide "the military forces needed to deter war and ensure our nation's security".

The Department of Defense is headed by the Secretary of Defense, a cabinet-level head who reports directly to the President of the United States. Beneath the Department of Defense are three subordinate military departments: the United States Department of the Army, the United States Department of the Navy, and the United States Department of the Air Force. In addition, four national intelligence services are subordinate to the Department of Defense: the Defense Intelligence Agency (DIA), the National Security Agency (NSA), the National Geospatial-Intelligence Agency (NGA), and the National Reconnaissance Office (NRO). Other Defense Agencies include the Defense Advanced Research Projects Agency (DARPA), the Defense Logistics Agency (DLA), the Missile Defense Agency (MDA), the Defense Health Agency (DHA), Defense Threat Reduction Agency (DTRA), the Defense Security Service (DSS), and the Pentagon Force Protection Agency (PFPA), all of which are under the command of the Secretary of Defense. Additionally, the Defense Contract Management Agency (DCMA) provides acquisition insight that matters, by delivering actionable acquisition intelligence from factory floor to the warfighter. Military operations are managed by ten regional or functional Unified combatant commands. The Department of Defense also operates several joint services schools, including the Eisenhower School (ES) and the National War College (NWC).

History