Resulting from an informal agreement on the Atlantic Charter of 1941, the secret treaty was renewed with the adoption of the BRUSA Agreement of 1943, before officially entering into force on 5 March 1946 by the United Kingdom and the United States. In the following years, it was extended to Canada, Australia and New Zealand. The alliance of intelligence operations is also known as The Five Eyes.      In classification markings, this is abbreviated to FVEY, with countries abbreviated as EN, CAN, NZL, GBR and USA respectively.  He added: “When the threat from Nazi Germany was replaced by a new one in the East, the agreement served as a basis for intelligence cooperation during the Cold War. The two nations, bound by common ties of history, culture and language, agreed not to collect information against each other, nor to tell “third parties” about the existence of the agreement. Details of the NSA`s agreement to share the personal data of US citizens with Israel`s UNSIL The UKUSA agreement was later extended to Canada in 1948 and to Australia and New Zealand in 1956. . .