November 21,2008: The U.S. National Security Agency (NSA) recently released documents detailing some of its successes in the past. It's normal for intelligence agencies to keep their successes, and failures, secret for a long time. The main reason that revealing these events would expose techniques that are still in use. The NSA specializes in code breaking (cryptography) and SIGINT (Signals Intelligence). Among the successes revealed were;

During the Cuban Missile Crises of 1962, when Russia secretly (the NSA didn't catch it) moved ballistic missiles to Cuba, the NSA did successfully track the readiness of Soviet missile, naval and ground forces through the late 1962 events. This played a major role in avoiding an escalation to nuclear war, and defusing the situation.

In 1968, the NSA detected the communist preparations for the Tet Offensive. However, president Johnson, military commanders and the CIA discounted this warning, believing that the communists would not attempt such a suicidal attack. The communists did, took heavy losses, and suffered a major defeat, but scored a propaganda victory when the U.S. media declared Tet  a communist victory.

In early 1975, the NSA detected North Vietnamese preparations for a conventional (infantry and tank divisions) invasion of South Vietnam. Again, American leaders discounted this as too aggressive (partly because the North Vietnamese had signed a peace treaty pledging to not do that sort of thing.) Again, communist duplicity and boldness resulted in victory.

In 1982, the NSA detected an unprecedented (since 1962) rise in the alert (readiness for combat) levels of Soviet ballistic missiles and conventional forces. This was a panic attack, based on misinterpreted information, within the Soviet leadership. The NSA warning enabled the U.S. to defuse the situation safely.

One of the most underestimated of the intelligence agencies. The NSA collects and sorts out "signals intelligence" (messages sent regularly by radio, telephone, Internet and so on) information. More importantly, NSA develops ciphers (methods to encode secret American messages) and decipher the secret codes of other nations. The United States has always been very good at breaking codes, but doing that is only useful if the other guy doesn't know you have broken his codes. The NSA was established in 1952 as a secret agency, and it was decades before the government officially admitted that it existed. Thus all the secrecy at NSA.