Much of the information exchange is done through STONEGHOST`s ultra-sensitive network, which is supposed to contain “some of the best-kept secrets in the Western world.”  In addition to establishing rules for the exchange of information, the agreement was formalized and the “special relationship” between the United Kingdom and the United States was consolidated.   The United Kingdom – United States of America Agreement (UKUSA, /ju-ku-s/ew-koo-SAH) is a multilateral signal intelligence cooperation agreement between the United Kingdom, the United States, Canada, Australia and New Zealand. The Secret Service Alliance is also known as Five Eyes.      In classification markings, this is abbreviated as an FVEY, with the individual countries being abbreviated as GBR, USA, CAN, AUS and NZL.  The UKUSA agreement was then extended to Canada in 1948 and to Australia and New Zealand in 1956. According to intelligence historian Richard Aldrich, the British tried to use the Commonwealth as an “equalizer” by convening Canadians and Australians at an intelligence summit in London before meeting the Americans, and shortly thereafter, Mi6 leader Stewart Menzies met with an American team led by Joseph Wenger at Bryanston Square in London to work on a bilateral agreement. “When the negotiations became sticky, Menzies kidnapped everyone for a bi-abacus lunch at the White`s Club and triggered his differences, as a result, refreshed,” says Aldrich. It could be said that during the Second World War, the United Kingdom and the United States began to cooperate fully on intelligence. On May 17, 1943, the British Government Code and Cipher School (GC-CS, forerunner of GCHQ) entered into a special intelligence cooperation agreement with the U.S. Department of War.
 Also known as the Brusa Agreement, its importance to the subsequent intelligence relationship cannot be underestimated. Bradley F. Smith describes the Brusa Agreement as “the written constitution highlighted by the Anglo-American Krypanalytic Partnership, which flourished over the last two and a half years of the Second World War and has remained in a modified form until today.”  BRUSA focused primarily on communications intelligence (COMINT) and the breaking of enemy codes during the war. For the first time, she established an intimate collaboration on COMINT at the highest level.  In addition to COMINT, the Security Coordination (BSC), an element of the Secret Intelligence Service (SIS), played a central role in the establishment of the Office of the Coordinator of Information (COI), the forerunner of the Office of Strategic Services (OSS) and, therefore, the Central Intelligence Agency (CIA).  It is clear that the British and American secret services were already closely linked in the 1940s. He added: “As the threat of Nazi Germany was replaced by a new one in the east, the agreement served as the basis for intelligence cooperation during the Cold War.