intelligence as well as human intelligence (HUMINT) and geospatial intelligence (GEOINT). Organisations The following table provides an overview of most of the FVEY agencies involved in such forms of data sharing. History Origins (1941–1950s) The earliest origins of the Five Eyes alliance are secret meetings between British and US code-breakers at the British code-breaking establishment at Bletchley Park in February 1941 (before the US entry into the war). A February 1941 entry in the diary of Alastair Denniston, head of Bletchley Park, reading "The Ys are coming!" ("Ys" referring to "Yanks") is the first record, followed by "Ys arrive" on 10 February. The British and US agencies shared extremely confidential information, including the British breaking of the German Enigma code, and the US breaking of the Japanese Purple code. From then key figures travelled back and forth across the Atlantic, including Denniston and code-breaking expert Alan Turing. The practical relationship established for wartime signals intelligence developed into a formal signed agreement at the start of the post-war Cold War. The formal Five Eyes alliance can be traced back to the Atlantic Charter, which was issued in August 1941 to lay out the Allied goals for the post-war world. On 17 May 1943, the British–U.S. Communication Intelligence Agreement, also known as the BRUSA Agreement, was signed by the UK and U.S. governments to facilitate co-operation between the U.S. War Department and the British Government Code and Cypher School (GC&CS). On 5 March 1946, the secret treaty was formalized as the UKUSA Agreement, which forms the basis for all signal intelligence cooperation between the NSA and GCHQ to this day. In 1948, the treaty was extended to include Canada, followed by Norway (1952), Denmark (1954), West Germany (1955), Australia (1956), and New Zealand (1956). These countries participated in the alliance as "third parties". By 1955, the formal status of the remaining Five Eyes countries was officially acknowledged in a newer version of the UKUSA Agreement that contained the following statement: The "Five Eyes" term has its origins as a shorthand for a "AUS/CAN/NZ/UK/US EYES ONLY" (AUSCANNZUKUS) releasability caveat. Cold War During the Cold War (generally accepted to be approximately the period 1947–1991), GCHQ and the NSA shared intelligence on the Soviet Union, the People's Republic of China, and several eastern European countries (known as Exotics). Over the course of several decades, the ECHELON surveillance network was developed to monitor the military and