[1] At the time that Fellwock blew the whistle on ECHELON, the NSA was a nearly unknown organization and among the most secretive of the US intelligence agencies.

[3] ECHELON is the name popularly given to the signals intelligence (SIGINT) collection and analysis network operated on behalf of the five signatory states (so called "Five Eyes" FVEY) to the UKUSA Security Agreement.

According to information in a European Parliament document "On the existence of a global system for the interception of private and commercial communications (ECHELON interception system)", ECHELON was ostensibly created to monitor the military and diplomatic communications of the Soviet Union and its Eastern Bloc allies during the Cold War in the early 1960s.

[4] Because of the Fellwock revelations, the U.S. Senate United States Senate Select Committee to Study Governmental Operations with Respect to Intelligence Activities ("Church Committee" as it was chaired by Frank Church) introduced successful legislation in 1973 to stop the NSA from spying on American citizens.

After the September 11 attacks, the law was amended, enabling President George W. Bush to expand the warrantless surveillance of American citizens.