On September 18, 1947, the National Security Act took full effect, creating the United States Department of Defense and the Central Intelligence Agency. The act reorganized the military by combining the War and Navy Departments into a single department headed by a Secretary of Defense. It also created the Air Force as an independent service and established the National Security Council. The CIA was tasked with coordinating foreign intelligence and covert operations. These changes reflected new security needs in the early Cold War and reshaped the structure of the U.S. national security state.
