Executive department of the U.S. federal government responsible for the armed forces and national security; headquartered at the Pentagon.
The United States Department of Defense (DoD) is an executive department of the U.S. federal government responsible for coordinating and supervising the armed forces (Army, Navy, Marine Corps, Air Force, Space Force). It was established in 1947 as the National Military Establishment under the National Security Act and received its current name in 1949. Its headquarters is the Pentagon in Arlington County, Virginia. The DoD is the world's largest employer, with approximately 2.86 million military and civilian personnel. Through agencies such as DARPA and the Chief Digital and Artificial Intelligence Office (CDAO), it is one of the world's largest funders of research into artificial intelligence, autonomous systems and robotics. In September 2025 a secondary designation "Department of War" and the war.gov domain were introduced, but the statutory name remains the Department of Defense.
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