National Security Agency

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NATIONAL SECURITY AGENCY (NSA) is a key institution within the U.S. intelligence community. The NSA's predecessor, the Armed Forces Security Agency (AFSA), was established within the Department of Defense (DOD) under the command of the Joint Chiefs of Staff on 20 May 1949 by Secretary of Defense Louis Johnson. In theory, the AFSA was to direct the communications intelligence and electronic intelligence activities of the signals intelligence units of the army, navy, and air force. In practice, the AFSA had little power.

On 24 October 1952 President Harry S. Truman signed a (later declassified) top-secret, eight-page memorandum entitled "Communications Intelligence Activities," which abolished the AFSA and transferred its personnel to the newly created National Security Agency. The creation of NSA had its origins in a 10 December 1951 memo from Director of Central Intelligence Walter Bedell Smith to National Security Council executive secretary James B. Lay stating that "control over, and coordination of, the collection and processing of Communications Intelligence had proved ineffective" and recommending a survey of communications intelligence activities. The study was completed in June 1952 and suggested a need for much greater coordination and direction at the national level. As the change in the agency's name indicated, the role of the NSA was to extend beyond the armed forces, to be "within but not part of DOD." In 1958, the NSA was also assigned responsibility for directing and managing the electronics intelligence activities of the military services.

Communications and Electronic Intelligence Operations

The charter for the NSA is National Security Council Intelligence Directive (NSCID) 6, "Signals Intelligence" (SIGINT), of 17 January 1972. It directed the NSA to produce SIGINT "in accordance with the objectives, requirements and priorities established by the Director of Central Intelligence Board." The directive also authorized the director of the NSA "to issue direct to any operating elements engaged in SIGINT operations such instructions and assignments as are required" and states that "all instructions issued by the Director under the authority provided in this paragraph shall be mandatory, subject only to appeal to the Secretary of Defense."

SIGINT includes two components: communications intelligence (COMINT) and electronic intelligence (ELINT). COMINT includes diplomatic, military, scientific, and commercial communications sent via telephone, radio-telephone, radio, or walkie-talkie. The targeted communications might be relayed via satellites, ground stations, or cables. ELINT includes the signals emitted by radar systems as well as by missiles during testing.

At the end of the twentieth century, NSA's headquarters at Fort George G. Meade in Maryland housed approximately twenty thousand civilian employees in three buildings. The NSA budget was approximately $4 billion annually. The NSA has two major directorates: the Directorate for Signals Intelligence and the Directorate for Information Assurance. In addition to the employees serving at NSA headquarters and NSA facilities oversees, the director of the NSA also guided (through the Central Security Service that he also heads) the SIGINT activities of approximately eighteen thousand army, navy, and air force signals intelligence personnel. Those military personnel were largely responsible for manning U.S. SIGINT ground stations around the world, some of which control and receive data from signals intelligence satellites, while others intercept signals from a variety of antennae at those sites.

The most important U.S. signals intelligence satellites are those in geosynchronous orbit, which essentially hover 22,300 miles above points on the equator. From that vantage point they can collectively intercept a vast array of signals from most of the earth. Some ground stations intercept the communications passing through civilian communications satellites. Other ground stations, such as those located in Korea and Japan, target high-frequency military communications in their part of the world.

Military personnel from air force and navy SIGINT units (the Air Intelligence Agency and Naval Security Group Command) also occupy key positions on board aircraft used to collect signals intelligence, including the air force's RC-135 RIVET JOINT aircraft and the navy's EP-3 ARIES reconnaissance planes. Both planes intercept communications and electronic signals. Another version of the RC-135, designated COMBAT SENT, focuses purely on electronic signals such as radar emanations.

Naval vessels, including surface ships and submarines, have been employed for decades to monitor communications and electronic signals. Ships were employed to intercept Nicaraguan communications during the Reagan administration (1981–1989) while submarines conducted highly secret intercept operations near and within Soviet waters from 1960 until the end of the Cold War. In addition a joint CIA-NSA organization, the Special Collection Service, conducts eavesdropping operations from U.S. embassies and consulates across the world, partly in support of CIA operations in those countries and partly for strategic intelligence purposes.

Specific Operations

Although the details of NSA intercepts are generally highly classified, information about some successes have leaked out over the years. The NSA intercepted Britain's communications during the 1956 Suez Crisis, Iraq's communications to its embassy in Japan in the 1970s, and Libya's communications to its East Berlin People's Bureau prior to the bombing of a West Berlin nightclub in 1986. Eavesdropping operations from the U.S. embassy in Moscow during the 1970s, the intelligence from which was designated Gamma Gupy, picked up conversations from senior Soviet leaders as they spoke from their limousines.

In addition, intercepts allowed the United States to piece together the details concerning the sinking of a Soviet submarine in the North Pacific in 1983. In 1988, intercepted Iraqi military communications led U.S. officials to conclude that Iraq had used chemical weapons in its war with Iran. After the Iraqi invasion of Kuwait in August 1990, COMINT and other intelligence reports indicated that some Saudi leaders were considering attempts to pay off Saddam Hussein.

The NSA's eavesdropping operations were often highly risky. In 1967 the USS Liberty, a ship operated by the navy on behalf of the NSA, was bombed by Israeli aircraft during the Six Day War in the Mideast. In January 1968, North Korea captured the USS Pueblo, holding its crew for approximately a year. In April 1969, North Korea shot down an EC-121 SIGINT aircraft. In 2001, the People's Republic of China detained the crew of an EP-3 after it was forced to land on Chinese territory after a collision with a Chinese fighter.

Assuring the Integrity of Intelligence

The NSA has a second major mission, originally known as Communications Security (COMSEC), but renamed Information Security (INFOSEC) in the 1980s and, subsequently, Information Assurance. In its information assurance role, NSA performs the same basic COMSEC functions as it did in the past. It creates, reviews, and authorizes the communications procedures and codes of a variety of government agencies, including the State Department, the DOD, the CIA, and the FBI. This includes the development of secure data and voice transmission links on such satellite systems as the Defense Satellite Communications System (DSCS). Likewise, for sensitive communications FBI agents use a special scrambler telephone that requires a different code from the NSA each day. The NSA's COMSEC responsibilities also include ensuring communications security for strategic weapons systems so as to prevent unauthorized intrusion, interference, or jamming. In addition, the NSA is responsible for developing the codes by which the president must identify himself to order the release of nuclear weapons. As part of its information assurance mission, the NSA is also responsible for protecting national security data banks and computers from unauthorized access by individuals or governments.


Aid, Matthew M. "The Time of Troubles: The US National Security Agency in the Twenty-First Century." Intelligence and National Security 15, no. 3 (Autumn 2000): 1–32.

Aid, Matthew M., and Cees Wiebes, eds. Secrets of Signals Intelligence during the Cold War and Beyond. London: Frank Cass, 2001.

Bamford, James. The Puzzle Palace: A Report on America's Most Secret Intelligence Organization. New York: Penguin, 1983.

———. Body of Secrets: Anatomy of the Ultra-Secret National Security Agency from the Cold War to the Dawn of a New Century. New York: Doubleday, 2001.


See alsoCentral Intelligence Agency ; Defense, Department of ; Intelligence, Military and Strategic .

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National Security Agency