Milestones: 1945–1952 - Office of the Historian

OnSeptember 18, 1947, President Truman signed the National Security Act. It established the CIA, the United States Air Force, the Department of Defense, and the National Security Council. An excerpt from the article:

"The act also established the Central Intelligence Agency (CIA), which grew out of World War II era Office of Strategic Services and small post-war intelligence organizations. The CIA served as the primary civilian intelligence-gathering organization in the government. Later, the Defense Intelligence Agency became the main military intelligence body. The 1947 law also caused far-reaching changes in the military establishment. The War Department and Navy Department merged into a single Department of Defense under the Secretary of Defense, who also directed the newly created Department of the Air Force. However, each of the three branches maintained their own service secretaries."