Berlin Tunnel

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Berlin Tunnel


The Berlin Tunnel involved an attempt by American and British intelligence to adjust to the late 1940s Soviet shift from wireless transmissions to landlines by tapping Soviet and East German communication cables via a tunnel dug below the communist sector of the German city. The tunnel, which lasted from March 1955 until its discovery by Soviet troops in April 1956, provided difficult-to-obtain military intelligence, as well as information about scientific and political developments behind the Iron Curtain.

The brainchild of the CIA, the Berlin Tunnel aimed to collect Soviet intelligence passed along an underground hub of telecommunications cables adjacent to the U.S. sector of the divided city. While Operation Gold had been conceived in 1951, detailed plans were not in place until August 1953 and the concept did not receive CIA approval until January 1954. The delays centered on the difficulty of discovering exactly which cables were used for Soviet communications and where these cables were located. While the CIA relied upon a number of East German sources to get information, a contact in the long-distance department of an East Berlin post office proved especially useful by providing books that identified cable users. Another contact in the East German Ministry of Post and Telecommunications provided detailed official maps of Soviet cable lines. Tunnel construction then began early in 1954.

The CIA, using the U.S. Army as a front, designed a warehouse that led to a subterranean passageway about 1800 feet long (900 feet into Soviet territory) and 16.5 feet deep. A West Berlin contractor built the warehouse under the misconception that the unusually deep basement and ramps to accommodate forklifts were part of a new and improved quartermaster warehouse design. A detachment of U.S. Army engineers dug the tunnel, but the British army drove the vertical shaft from the end of the tunnel to the target cables and British telecommunications experts made the actual tap. In order to disguise evidence of digging, the army installed washers and dryers on site to clean the fatigues of the construction workers. As a defense against possible Soviet attackers, a heavy torchproof steel door separated the preamplification chamber, where the signals were isolated for recording, and the vertical shaft of the tap chamber. A microphone in the tap chamber permitted security personnel to monitor any

activity in the area. Sandbags along the tunnel walls muffled sounds and served as shelves. Construction of the entire tunnel complex ended in March 1955 and the taps began in May.

The KGB soon became aware of Operation Gold through George Blake, a Dutch-born British double agent for the Soviets who entered MI-6 in 1953. Blake, employed in a technical division, gave information about the tunnel to the KGB when the project was still in the planning stages. In order to attack the tunnel, the Soviets would have to compromise Blake and they found it preferable to sacrifice some information rather than their valuable agent. The KGB did not inform anyone in Germany, including the East Germans or the Soviet users of the cable lines, about the taps. When Blake received a transfer in 1955, the Soviets were free to "discover" the tunnel.

Soviet and American accounts of the tunnel discovery do not match, with the Soviets creating a fanciful and widely-circulated account of Soviet technicians surprising Americans as they sipped coffee in the tunnel. In reality, with Blake safely out of the way, Soviet Premier Nikita Khruschchev planned to use the tunnel to score propaganda points but he did not wish to embarrass the British government on the eve of his visit to the island nation. He planned to emphasize the American role in the tunnel while downplaying British involvement. Accordingly, Soviet troops began to dig on the night of April 21, 1956. American personnel, using night vision equipment, detected 40 to 50 Soviet soldiers digging at three to five foot intervals. Given ample warning, the Americans retreated behind the steel door. The Soviets, unable to open the door, dug through an adjacent wall to get into the preamplification chamber. Once inside, they cut the tap cables and the microphone went dead.

Although it came to an embarrassing end, the Berlin Tunnel counts as a successful intelligence operation. The American and British governments used 50,000 reels of tape to capture 443,00 fully transcribed conversations (368,000 Soviet and 75,000 East German), which in turn led to 1,750 intelligence reports. Besides revealing the latest developments in Soviet atomic research, the tapes indicated disagreements between the Soviets and the East Germans over the status of West Berlin. Despite Soviet claims to the contrary, the tunnel provided much more than carefully planned misinformation.



Miller, Nathan. Spying for America: The Hidden History of U.S. Intelligence. New York: Paragon House, 1989.

Murphy, David E., Sergei A. Kondrashev, and George Bailey. Battleground Berlin: CIA vs. KGB in the Cold War. New Haven: Yale University Press, 1997.


CIA (United States Central Intelligence Agency)
Cold War (19501972)
KGB (Komitet Gosudarstvennoi Bezopasnosti, USSR Committee of State Security)
MI6 (British Secret Intelligence Service)

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Berlin Tunnel

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