The National Security Agency/Central Security Service (NSA/CSS), a cryptologic intelligence agency of the United States Department of Defense responsible for the collection and analysis of foreign communications and foreign signals intelligence, as well as protecting U.S. government communications and information systems, officially came into existence on November 4, 1952.
"The National Security Agency's predecessor was the Armed Forces Security Agency (AFSA), created on May 20, 1949. This organization was originally established within the U.S. Department of Defense under the command of the Joint Chiefs of Staff. The AFSA was to direct the communications and electronic intelligence activities of the U.S. military intelligence units: the Army Security Agency, the Naval Security Group, and the Air Force Security Service. However, that agency had little power and lacked a centralized coordination mechanism. . . . As the change in the security agency's name indicated, the role of NSA was extended beyond the armed forces" (Wikipedia article on National Security Agency, accessed 01-14-2012).