United States Department of Defense
The United States Department of Defense (DoD), sometimes historically referred to as the Department of War, is an executive department of the U.S. federal government. It is primarily responsible for coordinating and supervising all agencies and functions of the government directly related to national security and United States Armed Forces.
Establishment and Evolution
The DoD was formally established on September 18, 1947, when President Harry S. Truman signed the National Security Act of 1947. This act created the National Military Establishment, which was later renamed the Department of Defense on August 10, 1949. This reorganization included the merging of three cabinet-level military departments: Department of the Army, Department of the Navy, and Department of the Air Force.
Headquarters and Leadership
The DoD is headquartered at the Pentagon in Arlington County, Virginia. The department is headed by the United States Secretary of Defense, a cabinet-level official who reports directly to the President of the United States. The first secretary of defense was James V. Forrestal, confirmed on September 17, 1947.
The Deputy Secretary of Defense serves as the principal civilian deputy to the secretary, assisting in the overall administration of the department.
Mission and Components
The stated mission of the Department of Defense is "to provide the military forces needed to deter war and ensure our nation's security." It supervises the Army, Navy, Marine Corps, Air Force, and Space Force. For certain purposes, it also oversees the Coast Guard when it operates in a combat role.
Organizational Structure
The DoD has a complex organizational structure that includes various agencies and commands. Among these are the Joint Chiefs of Staff, who provide military advice to the secretary of defense, and the National Security Council, which was also established by the National Security Act of 1947.
Other significant components include various combatant commands, which are responsible for planning and conducting military operations across different global regions.