On Sunday, the New York Times reported that Russian submarines and spy ships are operating near vital undersea fiber-optic cables that transmit the majority of the planet’s communication and economic data.

The fear, the report stipulates, is that Russia might be looking for weak spots that could be attacked and severed during a conflict.

Though the tactics and threat are reminiscent of the Cold War, the Russians appear to be taking a page out of the book that the U.S. Navy and the NSA wrote in the 1970s in a series of undersea wire-tapping missions that became known as Operation Ivy Bells.

Briefly mentioned in the Times report, Operation Ivy Bells is written about extensively in the book “Blind Man’s Bluff: The Untold Story of American Submarine Espionage” by Sherry Sontag and Christopher Drew. The missions used submarines to listen in on previously untapped Soviet “hard-lines” to glean information about Soviet ballistic missile submarine deployments and strategy.

In 1970, at the height of the Cold War, James Bradley, the director of undersea warfare at the Office of Naval intelligence dreamed up one of the most daring submarine spy missions in modern history. He wanted to send the specially outfitted 350ft nuclear-powered submarine, the Halibut, to land over the ocean floor under the Sea of Okhotsk and tap a phone line that connected the Soviet submarine base at Petropavlovsk to its Pacific Fleet headquarters near Vladivostok.

Besides the risk of international incident if Halibut was caught or detected, there was no evidence that the phone line even existed. The only evidence that Bradley had was the notion that the sub base in Petropavlovsk was probably required to give constant updates back to its higher headquarters. So Bradley, sitting in his Pentagon office at 3 a.m., thought back to his childhood, racking his brain to figure out where the Soviets might have laid their cables.

According to “Blind Man’s Bluff,” Bradley, in his predawn stupor, recalled from his youth written signs that had been posted along the Mississippi River to mark undersea cables. The signs, posted along the shore, were meant to prevent passing from hooking the cables with their anchors.

With this in mind, Bradley reasoned that there had to be similar signs near the shallower points on the Sea of Okhotsk.

So, with Bradley’s childhood in mind, “the most daring acts of tele-piracy of the Cold War” was born.

After an extensive multi-year refit that began in the late 60s, Halibut was ready to depart from Mare Island Naval Shipyard outside of San Francisco for Okhotsk in 1972. One of the sub’s most noticeable additions was a giant hump mounted behind its conning tower, a hump that was publicly declared as a hangar for a deep sea rescue vehicle but was actually a “decompression and lockout chamber” for the team of divers that would exit the sub to tap the Soviet cables.

So in October 1972, the crew of Halibut made its way across the Pacific, its older nuclear reactor pushing her across the sea at just over 10 knots. First the spy sub moved north to the Aleutian Islands, then past the Bering Straight and into the Sea of Okhotsk. The captain of the Halibut, Navy Cmdr. Jack McNish, had not told the crew where it was going—only that they were leaving home for three months and that they were searching for the remnants of a new Soviet infared anti-ship missile that the United States was desperately seeking a counter-measure for.

Once inside the Sea of Okhotsk, the Halibut slowly patrolled with its periscope up, scanning the coastline for Bradley’s signage that would mark the cables. And then, after a week of patrolling with no luck, the Halibut found a sign on the northern shore of the Sea of Okhotsk that said something to the extent of “Do Not Anchor. Cable Here” in Russian.

The Halibut, after locating the sign, launched a specially designed submersible or “fish,” that then proceeded to search for the cables. The fish had a very basic video camera, and a higher definition camera. While the video was relayed in real-time back to the submarine, the film from the camera had to be retrieved from the fish and subsequently developed while the Halibut was near the surface so that the sub’s dark room could properly vent or “snorkel” the chemicals used to develop the film.

Hours after the fish’s launch, footage began to come back of foot-long bumps in the sand, a sort of Morse code etched in the sea bottom. The Halibut had found the cables.

According to “Blind Man’s Bluff,” the fish was then retrieved and the film developed, revealing the Soviet cables strewn along the seafloor.

After identifying the cables, McNish maneuvered the Halibut well outside the 3-mile territorial limit of the Soviet Union and located a spot just above the cable where he could lower the submarine’s two massive anchors in a sort-of hover.

Using specially designed rubber wet suits that fit loosely and were pumped full of hot water to counter the freezing temperatures of the Sea of Okhotsk, the divers departed the Halibut armed with pneumatic air-guns to blow debris off the cables and emergency oxygen bottles in case their “umbilical cords” that connected them back to the Halibut were severed.

The wire-tap, according to “Blind Man’s Bluff,” was three-feet long and composed of a tape recorder and a lithium ion battery. A connector would wrap around the cable and draw out the words and data through induction. There was no cutting into the cable.

For the next few hours the recording device attached to the cable relayed Soviet communications back to a select group of spies aboard the Halibut who would then, after the completion of the mission and a successful return to port, send the tapes to Fort Meade, Md, where they would be subsequently analyzed.

With the tap successful, the Halibut then moved to its secondary mission of locating the Soviet missile fragments before returning to port. With the mission a success, Bradley saw a future filled with taps around the globe that could record for months and years continuously, without the presence of an American sub to collect the data.

In August 1972, the Halibut departed once more for the Sea of Okhotsk to repeat the tap. This time, however, the sub was rigged with explosives in case the sub and her crew were ever compromised. This time too, according to Blind Man’s Bluff, McNish told his crew about their actual mission and the risks it entailed.

In the years following more submarines would be outfitted like Halibut, and they too would conduct similar wire-taps. Operation Ivy Bells had begun.