Defense, United States Department of

Defense, United States Department of

Defense, United States Department of, executive department of the federal government charged with coordinating and supervising all agencies and functions of the government relating directly to national security and military affairs. Based in the Pentagon, it is divided into three major subsections—the U.S. Army, the U.S. Navy, and the U.S. Air Force. Among the many Defense Dept. agencies are the Missile Defense Agency (see Strategic Defense Initiative), the Defense Advanced Research Projects Agency, the Defense Intelligence Agency, the National Geospatial-Intelligence Agency, and the National Security Agency. The department also operates several joint service schools, including the National War College.


The Dept. of Defense was created by the National Security Act of 1947 by combining the Depts. of War and Navy and was called the National Military Establishment; it became the Dept. of Defense when the act was amended (1949). James V. Forrestal pioneered in this reorganization. Under the act, the Secretary of Defense—appointed by the President with the consent of the Senate—supervises the entire military. Under the Secretary of Defense is the Joint Chiefs of Staff made up of its chairperson, a senior military officer, the heads of the three main services, and the Commandant of the Marine Corps. The Secretary of the Army, the Secretary of the Navy, and the Secretary of the Air Force—made cabinet members by the act of 1947—were subordinated (1949) to give the Secretary of Defense full cabinet authority over the department.


The new defense establishment received its first test in the Korean War. It was generally agreed that the department revealed a capability to react quickly to crisis, but there was criticism that too much reliance had been placed on strategic air forces and nuclear weapons to the neglect of conventional military forces. The Eisenhower administration, concerned about controlling military expenditures, emphasized deterring a nuclear attack with massive retaliation (see nuclear strategy), despite critics who advocated additional expenditures on conventional forces.

Under Secretary of Defense Robert S. McNamara (1961–68), the department aimed for a more balanced military program and established a new layer of civilian officials who imported civilian management techniques. In general, the administrations of Presidents John F. Kennedy and Lyndon Johnson aimed for a stronger conventional capability but still failed with their counterinsurgency strategy in the Vietnam War.

During the cold war, the Dept. of Defense became a major economic force, mostly through its massive purchases and research investments (see Defense Advanced Research Projects Agency). However, the breakup of the USSR and the resultant reductions in defense spending have negatively affected civilian industries that supplied the Dept. of Defense. By 1997 the department had begun a “defense reform initiative,” intended to streamline and modernize what had become one of the world's largest organizations.


See W. Millis, Arms and Men: A Study of American Military History (New York: Mentor Books),1956; C. W. Borklund, The Department of Defense (1968) and with G. Foster, Paradoxes of Power (1983).

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