OPERATION GOLD (also known as Operation Stopwatch by the British) was a joint 1950’s American-British operation which was funded by the United States and involved creating a secret tunnel half a kilometer long which entered the Soviet-occupied zone in East Germany. The tunnel was created so as to tap the telephone cables used by the Soviet and East German militaries as well as by civilian governmental personnel.
The idea was passed to the United States by the British who had previously created their own tunnel in Soviet-occupied Austria (code named Operation Silver). The tunnel was approximately one kilometer long and ran from Rudow, West Berlin to Alt-Glenicke in East Berlin. The almost $7 million dollar operation was implemented by the Central Intelligence Agency and Britain’s Secret Intelligence Service, also known as MI6. It was approximately 6 meters deep and was completed between September 2, 1954 and February 25, 1955 and operated for 11 months and 11 days. More than half a million calls were intercepted and the operation produced somewhere in the area of 50,000 tapes.
Unfortunately, the tunnels effectiveness was undercut by the fact that George Blake, a Soviet spy who was working in Berlin as a case officer for MI6, learned of the tunnel during a meeting between British and American officials in December 1953. Blake was the secretary keeping notes of the meeting and he informed his Soviet contacts of the operation’s existence. Rather than cease using the telephone cables (which may have exposed Blake), the Soviets were alleged to have instead used them to feed disinformation to the Americans for almost two years before “discovering” the tunnel in 1956 (although Blake asserted that 99% of the information gleaned from the taps were authentic).
The United States enjoyed both praise for the achievement and ridicule for the failure of the operation. Director of Central Intelligence Allen Dulles called it “one of the most valuable and daring projects ever undertaken” by the agency. The CIA was unaware that Blake had betrayed the British by revealing the existence of the tunnel until 1959 when they were made aware of it by the former Head of Polish Intelligence Michael Goleniewski who defected to the United States in 1961.
Details of the operation were kept secret with Dulles ordering that “as little as possible… be reduced to writing.”