Echelon documents released

The original 1946 secret treaty between the UK and US which set up the famous 'Echelon' listening system has been released.

The treaty dealt primarily with communications intercept information, known as signals intelligence or "sigint".

Back in the early days of UKUSA cooperation, many long-distance or international phone calls were carried by longhaul HF radio, and were comparatively easily intercepted by a worldwide network of listening posts.

The Register - Echelon Publication
http://www.theregister.co.uk/2010/06/25/
echelon_publication/

UK National Archives
http://www.nationalarchives.gov.uk/ukusa/

UKUSA Highlights Guide
http://filestore.nationalarchives.gov.uk/ukusa/
ukusa-highlights-guide.pdf

US National Security Agency
Declassified UKUSA Signals Intelligence Agreement Documents Available
http://www.nsa.gov/public_info/press_room/
2010/ukusa.shtml

Wiki - Echelon (signals intelligence)
http://en.wikipedia.org/wiki/
Echelon_%28signals_intelligence%29