Defense, Department of, is an executive department of the United States government. The Department of Defense directs the operations of the nation’s armed forces, including the Army, Navy, and Air Force.
The department’s leaders also advise the president on military matters. The department headquarters are in the Pentagon Building, which is in Arlington, Virginia, near Washington, D.C. The department’s website at https://www.defense.gov presents information on its activities.
Organization.
The Department of Defense is headed by the secretary of defense. The department also includes (1) the Joint Chiefs of Staff, (2) the military departments, and (3) the unified combatant commands.
The secretary of defense
is a member of the president’s Cabinet. The secretary is a civilian and is appointed by the president with approval of the United States Senate. The secretary’s assistants deal with such matters as acquiring and building weapons, developing and protecting military communications systems, gathering intelligence, planning strategy, and preventing the spread of nuclear weapons. The secretary of defense and the assistants of the secretary are supported in their work by a number of agencies of the Department of Defense.
The secretary is a member of the National Security Council and the North Atlantic Council. The National Security Council, part of the Executive Office of the President of the United States, advises the president on a wide range of security issues. The North Atlantic Council directs the North Atlantic Treaty Organization (NATO), a defense alliance to which the United States belongs. The secretary of defense maintains close contact with top officials in other parts of the U.S. government, especially the Department of State.
The Joint Chiefs of Staff (JCS)
consists of a chairman, a vice chairman, the chiefs of staff of the Army and Air Force, the Navy’s chief of naval operations, the commandant of the Marine Corps, and the chief of space operations for the Space Force. The JCS is the top military staff of the secretary of defense. Members of the Joint Chiefs of Staff serve as military advisers to the president, the National Security Council, and the secretary of defense.
The military departments
are the departments of the Army, Navy, and Air Force. The Marine Corps is included in the Department of the Navy, and the Space Force is included in the Department of the Air Force. Each military department is headed by a civilian secretary who administers the department under the authority, direction, and control of the secretary of defense. The military departments organize, train, equip, and maintain the readiness of their forces.
The unified combatant commands
carry out military missions. They consist of large forces from more than one branch of the U.S. military.
History.
In 1789, Congress established the Department of War to administer and conduct military affairs. In 1798, Congress separated the naval forces from the land forces, creating the Department of the Navy. The secretaries of both the Department of War and the Department of the Navy were Cabinet members who reported directly to the president.
During World War II (1939-1945), President Franklin D. Roosevelt directed United States combat forces through a Joint Chiefs of Staff, which functioned without a formal charter. The United States armed services cooperated with one another through unified commands that operated overseas. At home, however, the Army and Navy competed for scarce personnel and materials. The Army Air Forces also pressed for equal status with the Army and Navy.
The National Security Act of 1947 created the National Military Establishment. It was headed by a secretary of defense and had three military departments. The Department of War became the Department of the Army. The Army Air Forces became a separate service under a new Department of the Air Force. The Navy and Marine Corps continued under the Department of the Navy.
The secretary of defense became a member of the Cabinet and formulated general policies and programs for the National Military Establishment. The heads of the military departments also served on the Cabinet. In 1947, Congress formally chartered the Joint Chiefs of Staff.
In 1949, Congress set up the Department of Defense to replace the National Military Establishment. Congress removed the heads of the military departments from the Cabinet and provided that the military departments be administered separately under the direction of the secretary of defense.
