Spy vs Spy Week

Operation Gold

A tunnel and a media circus

One of the major parts of spying is intercepting and collecting communications from hostile nations. In the early 1950s, Berlin was probably the best places in Europe for the West to try to intercept communications by the Soviet Union and the Eastern Bloc countries. It was the largest city on the continent and communication lines from Western France to Eastern Europe and the Soviet Union were routed through Berlin. It became even more important in 1951, when the Soviets began switching their secure communications from wireless to encrypted land lines, especially all of their military traffic.

The CIA started to examine the situation, trying to figure out how to get at the traffic on the land lines. There were both overhead and underground lines being used, and the CIA decided that trying to tap into the underground lines was the better idea, being that they couldn’t be observed 24/7. In 1953, an agent working in the East Berlin telephone exchange patched an East Berlin telephone line into West Berlin one night, allowing the CIA to get a sample of what might be obtained from the traffic available. What they got was potentially valuable enough for CIA headquarters to proceed with planning on acquiring a full time covert tap.

In 1953 they received information from the Bundesnachrichtendienst about the location of a critical telephone junction that was less than six feet underground, where three cables came together close to the border of the American sector in West Berlin. The CIA and British SIS began making plans for digging a tunnel from the American Sector to the underground junction.

In August of 1953, a location in the American Sector was selected, and detailed plans for the tunnel were completed and a proposal drawn up for approval by DCI Allen Dulles. Approval was granted in January of 1954 for Operation Gold, and work on the tunnel began in February, using the construction of an Air Force radar site and warehouse as a cover. The tunnel was completed a year later, and the taps were in place and collecting data a short while later.

There was a problem, however. The Soviets knew about the tunnel before construction had even started.

In October of 1953, US Intelligence officers held a briefing for the British SIS, and in the audience was a KGB mole by the name of George Blake. Blake had been captured during the Korean War, and had been flipped by the KGB during his captivity.

While the KGB knew about the tunnel and the importance of the tap, their first priority was to protect Blake. Knowledge of the tunnel was closely guarded by the KGB, and neither the Soviet GRU nor the East German Stasi was informed. Rather than closing down the tunnel immediately, the Soviets tightened their security and began searching for the location of the tap, which they located in late 1955. Blake was transferred in 1955, which allowed the Soviets to  ‘accidentally’ discover the tunnel. On April 21 1956, after a big rainstorm deluged the area, a special signal corps unit began digging up the area, citing flooding as causing interference in the cables. By 12:30 the following day they had discovered a trapdoor in the bottom of the tap chamber, and Soviet and East German soldiers broke into the eastern end of the tunnel at 14:20, with a large media audience in attendance. The tunnel had been operation for eleven months.

The digging operation had been seen by observers on the roof the warehouse in West Berlin, and the tunnel was evacuated well before the Soviets had dug into the tap chamber. The operators also left a live microphone with the equipment in the tunnel in order to hear and record what happened. Cheeky bastards.

There were newspaper articles around the world showing photographs of the tunnel, and the Soviets and East Germans called it “a criminal act” and “a violation of international law”, yada yada yada. Typical cold war kabuki.

A tremendous amount of information had been collected while the tunnel was in operation, some 50,000 reel to reel tapes comprising around 40,000 hours of telephone conversations and 6 million hours of teletype traffic were recorded. Processing the data took a further two years after the tunnel was shut down.

It wasn’t until 1961 when Blake was arrested that the CIA discovered how early that the tunnel had been compromised. There was much speculation about the likelihood that the Soviets used the tunnel for disinformation, and the data was closely examined afterwards. It was finally determined that the data collected was genuine, although with the KGB files on the incident still closed, one can’t help but wonder.



The Central Intelligence Agency Library



  • It's interesting that we had to re-learn the lessons of the 1940s in the 2000s. As Wi-Fi became more and more prevalent, people had to learn that transmissions through the ether were much more susceptible to interception and nefarious activity than interceptions via wires.

    • The Professor

      Yes, as a people, we don't seem to learn from history very well, do we.

  • OA5599

    "A tremendous amount of information had been collected while the tunnel was in operation, some 50 reel to reel tapes comprising around 40,000 hours of telephone conversations and 6 million hours of teletype traffic were recorded."

    In the 1980's a friend worked at a radio station that was programmed by their corporate headquarters. They had a bank of four reel-to-reel tape players, and each tape would hold four hours of music recorded at corporate (announcers were live and commercials and promos were played from cartridges). The reels were more than a foot in diameter.

    Granted, these mid-80's recordings were broadcast quality, but was technology really that advanced three decades prior that they could compress 800 hours of conversation onto a single tape?

    • The Professor

      That's a really good question, and I don't have an answer as yet. When I was researching this article, that number for the amount of tapes stood at odds with amount of data I was reading about elsewhere. It might be just simple misinformation to keep the actual nature of the recording equipment that was used a secret. Or, maybe they used reel-to-reel tapes that were 4 feet across, but I kind of doubt it. If I can come up with an answer that makes sense, I'll post it.