Department of Defense

Department of Defense
United States Department of War · Public domain · source
Agency name	Department of Defense
Seal width	200
Formed	18 September 1947
Preceding1	Department of War
Preceding2	Department of the Navy
Headquarters	The Pentagon, Arlington County, Virginia
Employees	~2.86 million (2023)
Budget	$842 billion (FY 2024)
Minister1 name	Lloyd Austin
Minister1 title	Secretary
Chief1 name	General Charles Q. Brown Jr. (USAF)
Chief1 title	Chairman of the Joint Chiefs of Staff
Chief2 name	Kathleen Hicks
Chief2 title	Deputy Secretary

Department of Defense. It is the executive branch department and principal national security institution responsible for coordinating and supervising all agencies and functions of the U.S. military. Headquartered at The Pentagon in Arlington County, Virginia, it was established by the National Security Act of 1947, succeeding the older Department of War and subsuming the Department of the Navy. The department is headed by the Secretary of Defense, a civilian appointed by the President and confirmed by the Senate, who is a key member of the President's Cabinet and the National Security Council.

History

The department's creation was a direct result of lessons learned from World War II, aiming to unify the Army, Navy, and newly independent Air Force under a single secretary. The National Security Act of 1947 initially created the National Military Establishment, which was renamed in 1949. Key subsequent legislation includes the Goldwater–Nichols Act of 1986, which dramatically reformed command structures by strengthening the role of unified combatant commanders. Its history is marked by overseeing military operations during the Cold War, the Vietnam War, the Gulf War, the War in Afghanistan, and the Iraq War.

Organization

The department is organized into three primary branches: the Office of the Secretary of Defense (OSD), the Joint Chiefs of Staff (JCS), and the Combatant Commands. The OSD is the principal staff element, containing numerous under secretaries and assistant secretaries for policy, acquisition, intelligence, and personnel. The Joint Chiefs of Staff includes the Chairman, the Vice Chairman, and the service chiefs of the Army, Navy, Air Force, Marine Corps, and Space Force, and the Chief of the National Guard Bureau. The nine combatant commands, such as U.S. Central Command and U.S. Indo-Pacific Command, are responsible for operational military missions.

Leadership

Civilian leadership is vested in the Secretary of Defense, currently Lloyd Austin, and the Deputy Secretary, Kathleen Hicks. The senior military officer is the Chairman of the Joint Chiefs of Staff, Charles Q. Brown Jr., who serves as the principal military advisor to the President, the Secretary of Defense, and the National Security Council. This structure ensures civilian control of the military, a foundational principle of the U.S. Constitution.

Budget

It administers one of the world's largest institutional budgets, with discretionary spending authority provided annually by the U.S. Congress. The FY 2024 budget request was approximately $842 billion, funding personnel, operations, maintenance, procurement of new systems like the F-35 Lightning II, and extensive research and development through agencies like the Defense Advanced Research Projects Agency (DARPA). The budget process involves detailed justification to committees including the House Armed Services Committee and the Senate Armed Services Committee.

Responsibilities and operations

Its primary mission is to provide the military forces needed to deter war and ensure the security of the United States. This encompasses a global presence, nuclear deterrence, cyber operations through U.S. Cyber Command, special operations via U.S. Special Operations Command, and extensive humanitarian assistance and disaster relief efforts, such as those following Hurricane Katrina or the 2011 Tōhoku earthquake and tsunami. It also manages the Defense Intelligence Agency and the National Security Agency.

Major components

The department consists of three military departments: the Department of the Army, the Department of the Navy (which includes the Marine Corps), and the Department of the Air Force (which includes the Space Force). Each department is separately organized under its own civilian secretary but is subordinate to the overall authority of the Secretary of Defense. Other major agencies include the Defense Logistics Agency, the Missile Defense Agency, and the combat support agencies like the National Geospatial-Intelligence Agency. Category:United States Department of Defense Category:1947 establishments in the United States Category:National Security Council