The submarine that tapped the Soviets’ phone

During the Cold War, numerous espionage missions were carried out by submarines. Some of these episodes could form part of the plot of a James Bond movie, but the details surrounding them are still shrouded in military secrecy. Only a few have come to light, such as Operation Ivy Bells in the 1970s. In a nutshell, the idea consisted of nothing less than tapping a telephone cable linking the Soviet submarine fleet headquarters in Vladivostok with the Pacific Fleet’s base at Petropavlovsk. History attributes the original idea to Captain James Bradley, who was serving as undersea warfare director at the Office of Naval Intelligence. Legend has it — or perhaps it was reality — that he had the inspiration one sleepless night alone in his office at the Pentagon, when he realized that there had to be a rapid communication channel between the command and the operational bases. Although radio transmissions were undoubtedly used, they were more sensitive to intrusion (satellites capable of picking them up were beginning to come into use); a simple cable seemed much more secure.

The Petropavlovsk enclave is located near the tip of Kamchatka, where it opens onto the desolate Sea of Okhotsk. This is a huge expanse of water, three times the size of Spain, enclosed between the peninsula and the coast of the mainland and frozen for most of the year, therefore with little commercial traffic except in the summer months. Further north, in an even more inaccessible inlet, the nuclear submarine base was located. It was abandoned years ago, but during the Cold War it could house a dozen submersibles.

The cable, if it existed, would reach the Pacific submarine fleet command in Vladivostok; a hose of copper wires snaking 2,500 kilometers along the bottom of the Sea of Okhotsk. The problem was locating it. Bradley guessed that at the point on the coast where the cable plunged into the sea there would be some anchoring prohibition to ensure it was not damaged. It was enough to find the sign warning vessels not to drop anchor.

For that, one had to enter Russian territorial waters, a politically very risky operation at a time when U.S. President Richard Nixon was trying to reach disarmament agreements. But the prospect of eavesdropping on conversations between Soviet admirals was so tempting that Henry Kissinger himself gave the go-ahead to carry it out with the utmost secrecy.

The mission was entrusted to the submarine USS Halibut under the command of Commander Jack McNish. It was a ship with experience in secret operations; it had participated in the search for — and location of — a sunken Soviet submersible in the Pacific and had very advanced tracking equipment for the time: a kind of wire-guided torpedo equipped with sonar and cameras. On board, a small group of specialists with all the necessary security credentials were in charge of operating them; the rest of the crew knew nothing of their true mission.

A mini-submarine

Astern, the Halibut carried a device that looked like a rescue mini-submarine. In reality, it was welded to the deck; it was a hyperbaric chamber prepared to use the new mixture of oxygen and helium. It was a recent development, which made it possible to combat the toxicity of oxygen at high pressures and the danger of nitrogen embolism. With this breathing equipment, divers could move along the sea floor, at a depth of about 120 meters, although the preparation process to eliminate all the nitrogen from their blood was gruelling; hours or even days of confinement in the hyperbaric chamber.

Equipped with an old reactor, the Halibut was not a fast submarine and even less so with the mammoth she carried at the stern. Moving at barely 10 knots, it took almost a month to reach Okhotsk, where the vessel stealthily entered rough waters and began to scan the coastline, inspecting it meter by meter with a periscope, making sure that no accidental reflection on the glass would reveal its presence; although the truth is that the area was so desolate that hardly anyone could have spotted it.

It took them a week to find the point where the cable entered the water. Immediately, one of the reconnaissance torpedoes was launched, which would pick up images of the hose half buried in the sand. Once its course was plotted, the Halibut slipped out into the open sea, away from territorial waters.

When the sounder was about 120 meters deep, the Halibut dropped two heavy anchors that would keep it stationary at a shallow depth. It was the turn of the divers, equipped with thermal suits to protect them against the freezing temperatures, air supply hoses, lights and — crucially — safety cables to be able to pull them back in if they were swept away by the current. Using compressed air blowers, they removed the sand that hid the cable and installed an electronic device around it that would listen to the conversations circulating inside. Or at least from some of the many lines that it was comprised of.

The U.S. Navy had taken every possible precaution to avoid accusations of espionage, which could border on outright piracy. The Soviet cable was neither cut nor damaged; the tapping was done by induction, taking advantage of a debatable American law that did not consider it illegal to pick up signals that escaped the communications device. Naturally, everyone involved knew that in practice this subterfuge lacked the slightest legal basis.

For days the device continued to listen to the conversations flowing through that copper hose. Some were of strategic value: maintenance programs, patrol areas, departures and arrivals of this or that submarine... others, mere inconsequential chatter about family matters or simply longing comments from a sailor anxious to return home. The shelf-life of the contraption would be short; as long as its batteries would allow. But the important thing was that the possibility of snooping with impunity on a secret communication line had been demonstrated.

Shortly before the appointed day of departure a tremendous storm broke out in the Sea of Okhotsk. Waves of between six and eight meters swept over the ocean causing the submersible to rock, held only by its two bottom anchors. In the end, as if to add drama in an action movie, both cables snapped and the Halibut was free to float to the surface, despite all the efforts of the dive plane operators.

At the time, divers were outside, dragged by their own hoses and the safety ropes that connected them to the submarine. If they gained too much height, the sudden decompression could be fatal, so the commander gave the order to flood the ballast tanks. The Halibut sank suddenly, landing violently on the bottom. A situation that was not very reassuring, since the sand could block the reactor’s cooling water intakes.

The submarine remained on the bottom until the storm subsided. It then executed a complicated maneuver that involved emptying the ballast tanks to force an emergency ascent, but immediately re-flooding them so as not to break the surface, risking possible detection.

The Halibut did not return directly to its base. It had spent a few days earlier trying to pick up fragments of anti-ship missiles that the Soviet Union was testing in those waters; thousands of them, some only a few centimeters long. The hope was to be able to identify debris from the new infrared sensors that would allow them to head for their targets; probably the big American aircraft carriers. But no luck. They gathered pieces of metal, bow warheads, and altimeter electronics, but no trace of infrared detectors were obtained. Later it would be discovered that those missiles did not use such guidance systems.

The possibilities opened up by the Halibut operation were so extraordinary that the U.S. Navy intelligence department commissioned Bell Laboratories to construct another, much more elaborate wiretap. The result was a cylinder, three meters long and one meter in diameter, filled with electronic equipment capable of identifying conversations flowing on either line. The data would be recorded on magnetic tape (its reels alone were one meter in diameter) and nothing less than a small plutonium nuclear reactor would be used to power it. Teams of divers would visit it periodically to collect the recordings and, if necessary, carry out repairs.

The Halibut returned to the Sea of Okhotsk twice more, in 1974 and 1975. On those occasions it was fitted with skis on its underside that allowed it to gently settle on the bottom. It also had demolition charges attached to its hull, in case it was detected.

Later, other submarines would take its place, in a back-and-forth that lasted almost 10 years. In 1981, American surveillance satellites detected a concentration of Soviet ships equipped with cranes and other rescue systems just above the spot where the device was located. Another submarine, the USS Parche, was sent to recover it before the whole rig was discovered, but it arrived too late. The Russians had already raised it and it was on its way to Moscow.

Once analyzed, the device ended up as a trophy. For years, it would be displayed in the Moscow Armed Forces Museum, alongside the remains of Gary Powers’ U-2 — another famous fiasco in the history of espionage — and the remains of a Tomahawk missile. In case there was any doubt as to its provenance, a label attached to the inside of the cylinder proclaimed “Property of the United States Government.”

How could the Russians have found it? As in all good spy movies, it was the work of a mole, a former employee of the U.S. National Security Agency. His name was Ronald Pelton and he was experiencing financial difficulties and saw no better solution to his problem than to sell his knowledge to Moscow. He had no documents to offer, but he did have a good memory of where the listening system had been installed. In return he received $35,000.

Pelton was arrested and sentenced to three life sentences, but he was released after serving 30 years in prison. He died just a couple of years ago. Captain Bradley, the mastermind of the operation, died in 2002 without public recognition of his exploits. The Halibut’s commander, Jack McNish, died in 2015. By then, his submarine had been decommissioned and scrapped without further ceremony.

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