Department of DefenseGovernment

The Department of Defense (DoD) is a cabinet-level executive department of the United States federal government responsible for coordinating and supervising all agencies and functions directly related to national security and the armed forces. Headquartered at the Pentagon in Arlington, Virginia, its mandate is to provide the military forces needed to deter war, defend the homeland, protect American vital interests abroad, and command the Army, Navy, Marine Corps, Air Force, and Space Force. Established by the National Security Act of 1947 as the National Military Establishment under President Harry S. Truman—unifying the historic Department of War (founded in 1789) and Department of the Navy (founded in 1798)—it was officially renamed the Department of Defense in 1949.