The National Security Agency (NSA) was founded in 1952 by President Truman. As a separately organized agency within the Department of Defense, NSA plans, coordinates, directs, and performs signals intelligence and information security functions in support of both Defense and non-Defense US Government activities. NSA was designated a Combat Support Agency in 1988 by the Secretary of Defense in response to the Goldwater-Nichols Department of Defense Reorganization Act.
The ability to understand secret foreign communications while protecting our own--a capability in which the United States leads the world--confers a unique competitive advantage. The skill to accomplish this is cryptology, the fundamental mission and core competency of NSA. NSA is charged with two complementary tasks: exploiting foreign electromagnetic signals and protecting the electronic information critical to US national security. "Exploiting" is referred to as signals intelligence; "protecting" is known as information systems security. Maintaining this global advantage requires preservation of a healthy cryptologic capability in the face of unparalleled technical challenges.
In the signals intelligence (SIGINT) role, NSA intercepts and analyzes foreign electromagnetic signals--many of them protected by codes, ciphers, and complex electronic countermeasures--to produce intelligence information for decisionmakers and military commanders. The focus is on interpretation of three broad types of signals: communications, such as telephone or teleprinter messages; non-communications signals, such as radars; and telemetry, the signals associated with missiles, weapons systems and space vehicles.
Following initial efforts during World War I and intermittent development between the wars, SIGINT came of age during World War II, when the US broke the Japanese naval code and learned of plans to invade Midway Island. This intelligence enabled the US to defeat Japan's superior fleet. Subsequent use of signals intelligence helped shorten the war by at least one year. The SIGINT organizations of the armed services were merged in 1952 to form NSA.
Information systems security (INFOSEC) involves the protection of all classified information that is stored or sent through US Government equipment, including computers, telephones, and other message-sending devices. INFOSEC professionals go to extraordinary lengths to make sure these systems remain impenetrable. NSA is also charged with a role in operations security (OPSEC)--to train other Government agencies to improve the security of their operations. Principally, this involves teaching employees of these agencies to see themselves as their adversaries do, and to use common sense to defend against espionage.