Operation Gold

Operation Gold (also known as Operation Stopwatch by the British) was a joint operation conducted by the American Central Intelligence Agency (CIA) and the British MI6 Secret Intelligence Service (SIS) in the 1950s to tap into landline communication of the Soviet Army headquarters in Berlin using a tunnel into the Soviet-occupied zone. This was a much more complex variation of the earlier Operation Silver project in Vienna. The plan was activated in 1954 because of fears that the Soviets might be launching a nuclear attack at any time, having already detonated a hydrogen bomb in August 1953 as part of the Soviet atomic bomb project. Construction of the tunnel began in September 1954 and was completed in eight months. The Americans wanted to hear any warlike intentions being discussed by their military and were able to listen to telephone conversations for nearly a year, eventually recording roughly 90,000 communications. The Soviet authorities were informed about Operation Gold from the very beginning by their mole George Blake but decided not to "discover" the tunnel until April 21, 1956, in order to protect Blake from exposure. Some details of the project are still classified, and whatever authoritative information could be found was scant until recently. This was primarily because the then-Director of Central Intelligence (DCI), Allen Dulles, had ordered "as little as possible" to be "reduced to writing" when the project was authorized. In 2019, additional specifics became available.