ECHELON is a the name used to describe an electronic surveillance and analysis network operated by the five signatory states to the UK-USA Security Agreement (Australia, Canada, New Zealand, the United Kingdom, and the United States). The five governments are evasive when asked about the existence of such a network.
Distributed across the world in a number of sites, the ECHELON system is thought to be capable of monitoring radio, satellite, microwave and mobile phone communications wirelessly, as well as tapping into undersea communication lines. Many even suggest that all the major internet backbones are routed through ECHELON systems, allowing unprecedented monitoring of internet traffic. ECHELON installations are though to include Menwith Hill (UK), Sugar Grove (US), GCSB Waihopai (NZ) and even Area 51.