The United Kingdom – United States of America Agreement (UKUSA, ) is a multilateral agreement for cooperation in signals intelligence between Australia, Canada, New Zealand, the United Kingdom, and the United States. The alliance of intelligence operations is also known as the Five Eyes. In classification markings this is abbreviated as FVEY, with the individual countries being abbreviated as AUS, CAN, NZL, GBR, and USA, respectively. Emerging from an informal agreement related to the 1941 Atlantic Charter, the secret treaty was renewed with the passage of the 1943 BRUSA Agreement, before being officially enacted on 5 March 1946 by the United Kingdom and the United States. In the following years, it was extended to encompass Canada, Australia, and New Zealand. Other countries, known as "third parties", such as West Germany, the Philippines, and several Nordic countries, also joined the UKUSA community in associate capacities, although they are not part of the mechanism for automatic sharing of intelligence that exists between the Five Eyes. Much of the sharing of information is performed via the ultra-sensitive STONEGHOST network, which has been claimed to contain "some of the Western world's most closely guarded secrets". Besides laying down rules for intelligence sharing, the agreement formalized and cemented the "Special Relationship" between the UK and the US. Due to its status as a secret treaty, its existence was not known to the Prime Minister of Australia until 1973, and it was not disclosed to the public until 2005. On 25 June 2010, for the first time in history, the full text of the agreement was publicly released by the United Kingdom and the United States, and can now be viewed online. Shortly after its release, the seven-page UKUSA Agreement was recognized by Time magazine as one of the Cold War's most important documents, with immense historical significance. The global surveillance disclosure by Edward Snowden has shown that the intelligence-sharing activities between the First World allies of the Cold War are rapidly shifting into the digital realm of the Internet. History Origins (1940s–1950s) The agreement originated from a ten-page 1943 British–US Communication Intelligence Agreement, BRUSA, that connected the signal intercept networks of the UK Government Communications Headquarters (GCHQ) and the US National Security Agency (NSA) at the beginning of the Cold War. The document was signed on 5 March 1946 by Colonel Patrick Marr-Johnson for the UK's London Signals Intelligence Board and Lieutenant General Hoyt Vandenberg