Digging for Gold – in Berlin

Military operations – overt and covert – come with risks.  But even covert military operations sometimes include too many ties to governments to be politically acceptable.  Hence, most intelligence services have “special” branches.

The US is no different.  And during the Cold War, these “special branches” of our intelligence community did some truly interesting and high APF work.  Many such operations succeeded; some didn’t.

The failures are the ones that we often hear about.  This is because they are often the ones exposed.  In contrast, the successful operations tend to stay secret for a rather long time.

This article is about one such clandestine operation.  A few years ago, it was publicly acknowledged and information about it declassified.

It occurred in Berlin during 1954-1956.  It was referred to as Operation Gold, and despite its early exposure is regarded as one of the most successful Cold War US covert operations.  It involved tunneling 450 meters into East Berlin – under one of the most heavily-guarded borders in the world – to tap telephone cables used by the Soviet military that were less than 2 meters (approx 6’ 6”) underground.

 

Yes, the APF on this operation – particularly during the tunneling and tap placement – was indeed high.  Cojones muy grandes required.

Introduction

Operation Gold was a joint operation conducted by the US and British intelligence services.  The British had conducted a similar operation in Vienna, Operation Silver, which allowed them to tap cables leading to the Soviet military headquarters in the then-Soviet occupation sector of Austria.  (Operation Silver continued until the Austrian government resumed sovereignty at the end of Allied occupation in 1955.) The British proposed conducting a joint operation to do the same in Berlin if a suitable location could be found at which to place taps.

Doing so would provide a windfall of intelligence on Soviet intentions in Germany and Eastern Europe.  This intelligence take would include not only voice communications, but also secure military message traffic.  Though US cryptographers had apparently not broken Soviet encryption systems of the day, there was still a vulnerability that could nonetheless  be exploited.   Soviet encryption equipment used at the time inadvertently broadcast a faint echo of the clear-text for encrypted messages along with the transmitted encrypted traffic.  Under the right conditions, this faint echo could be recovered with appropriate equipment and filtration.

In 1953, action became feasible.  The Allies learned hat three major communications cables in the Soviet sector came together in a single location that was a relatively short distance (less than 450 meters ) from the border between the Soviet and US secorts of Berlin.  The operation was thus determined feasible.  Approval was swift, and the operation began.

Pre-Tunnel Preparations

A suitable location was found in the US sector of Berlin for the tunnel’s support facilities.  At this location, a new “warehouse” with an unusually large basement (12’ ceilings) was constructed.  This building would house the tunnel’s support facilities as well as store the large (approx 3,100 tons) amount of soil that was expected to be excavated during the building of the tunnel.

In order to provide secrecy, a cover story was prepared – though it wasn’t circulated publicly.  The “warehouse” was intentionally constructed with poorly-camouflaged antenna, simulating a badly-disguised radio intercept station.  The hope was that the Soviets would “see through” the poor attempts at camouflage and misidentify the facility as a radio intercept station.

Execution

Construction of the tunnel began in 1954.  A 5 1/2 meter (18-foot) diameter shaft was sunk inside the warehouse to a depth of 6  meters (20 feet).  At that point, a horizontal shaft 2 meters (6 1/2 feet) in diameter was begun towards the cable junction point in the Soviet sector of Berlin.

Tunneling through the soil was slow and painstaking, as the soil was relatively soft and digging perforce had to be done quietly.  The tunnel was shored with 125 tons of steel and 1,000 tons of grout or cement (different sources say one or the other) to ensure it did not collapse under traffic and other loads.  Pumps were used to remove collected water.  Concrete and steel antipersonnel doors were installed at the sector border – as were explosive charges that could be used to collapse the tunnel if required.

By 28 February 1955, the cable tap location had been reached and tap placement began.  Tap placement was likewise slow.  However, by 10 March 1955, collection of traffic had begun.

Operations and Exposure

The tapping operations produced a bonanza of strategic- and operational-level intelligence.  In addition to traffic to/from the Soviet headquarters near Berlin (Zossen), conversations between the Soviet Embassy and Moscow and between East German and Soviet authorities were also intercepted.

Operations continued for a period of 11 months and 11 days.  At that point – on 21 April 1956 – an East German crew “conducting routine maintenance” on the cables discovered the taps.  While it took a few hours for the crew to recognize precisely what they were looking at, Soviet authorities were notified some hours after the discovery.

The Soviets publicized the tunnel at the time of discovery.  The Free World essentially laughed, considering it an audacious effort on the part of the US.

Post-discovery processing of collected intelligence continued for a substantial period of time.  At that point, the operation was thought ended.

But several years later, the operation came back to life – when the plot took a very new and unexpected twist.

Aftermath

It turned out that the 1956 “exposure” of Operation Gold – wasn’t.  The Soviets had known much if not all about the tunnel all along.

A highly-placed Soviet mole in British Intelligence, George Blake, had been involved in early planning meetings concerning Operation Gold.  (Blake had been captured in Korea during the Korean War and had spend roughly 3 years in captivity; it is believed he was “turned” then.)  He tipped the Soviets to the tunnel’s existence before construction began.

The Soviets apparently decided that Blake – who was very highly placed in MI-6 – was worth more than the information they would lose if they allowed the operation to proceed unmolested.  In order to protect Blake  from exposure, they did exactly that until after Blake had been reassigned to another job within British Intelligence.  The tunnel was not “discovered” by a maintenance crew until after that had occurred.

Blake was eventually exposed as a Soviet mole in 1961 by Polish defector Michael Goleniewski.  At that point, the US intelligence community conducted an extensive cross-check information obtained via Operation Gold to attempt to determine whether any of it was deliberate “disinformation”.  This analysis indicated that, as best could be determined, the intelligence obtained by the tunnel operation had been genuine.  The Soviets apparently really did think Blake was placed highly enough within British Intelligence to be worth exposing the 440,000+ telephone conversations, 6,000,000 hours of teletype traffic, and 1,750 intelligence reports collected by Operation Gold.

 

Well done, men.  Damn well done indeed.

 

 Sources

The Wikipedia article on Operation Gold is a decent though perhaps mildly inaccurate and biased starting point concerning the Berlin Tunnel.

The CIA has a brief summary of the operation posted on its website.  It’s better, but still short on details.

NSA has perhaps the best publicly-available information on Operation Gold, which they called Operation REGAL.  A short summary of the operation from the NSA perspective can be found here (Part I), here (Part II) and here (post-exposure discussion).  A much longer and more detailed description from NSA’s perspective can be found here.

Category: Historical