In April 1974, the United States and the UK agreed to the constuction of a SOSUS station, known as NAVFAC Brawdy, alongside the RAF base at Brawdy in Wales. It was one of a number of stations that monitored a growing chain of undersea microphones or "hydrophones" that were designed to pinpoint Soviet submarines as they moved out of their home waters into the Atlantic. SOSUS was one part of a three fold effort to track Soviet submarines. The second component was airborne search aircraft, including the RAF's Nimrod MR2 search aircraft. The third and most secret component was an effort to track the communications signals of Soviet strategic submarines when they rose to communicate with Moscow. This latter sigint effort was codenamed "Project Sambo" and involved twenty-two listening station provided by the American and eight provided by various allies. It was one of the highly secret projects reportedly revaled by Geoffrey Prime, who spied for the KGB in the 1970s. In 1995 the Joint Maritime Facility at St. Mawgan in Cornwall replaced NAVFAC Brawdy and the facility was deactivated on 1 October 1995.
Brawdy is now the headquarters for the British Army's 14 Signals (Electronic Warfare) Regiment