If you do a search on "Operation Ivy Bells" you should find some interesting articles about the whole operation, and how it eventually came to an end.
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Operation Ivy Bells
In the early 1970's, the U.S. government learned of the existence of an undersea cable running parallel to the Kuril Islands chain, connecting the major Soviet naval bases at Vladivostok and Petropavlovsk. At this time during the Cold War, the Sea of Okhotsk was aggressively claimed by the Russians as territorial waters, off limits to foreign vessels - especially U.S. warships. To this end, the Soviet Navy constructed a net of sound detection devices along the sea floor to warn of any unwanted visitors. Additionally, the entire area was the location of frequent surface and subsurface naval exercises. Nonetheless, despite these formidable obstacles, the potential for an unprecedented windfall of intelligence was simply too great to pass up.
Thus, a joint Navy-National Security Agency (NSA) mission was initiated, code-named Operation Ivy Bells, involving the use of U.S. Navy fast attack submarines working in conjunction with specially-trained Navy combat divers. Working in tandem, they would make monthly incursions into these dangerous waters to "tap" the line. One of the first such missions involved the USS Halibut (SSN-587) and the installation of a miniaturized, waterproof pod on the cable. This "wrap around" device, developed by the NSA, could eavesdrop on - and record - all communications passing through the line without the need for actually penetrating the wires inside. This capability was deemed necessary to prevent any possible damage to the cable that might then attract unwanted attention. In the event that the Russians chose to perform routine maintenance, the pod was designed to break off and fall to the sea bed in the event the line was raised for any reason.
Once the device was in place, subsequent missions were required in which a submarine would return to the location to pick up the six to eight weeks' worth of recordings inside the pod. For this operation, the frogmen would depart the sub's escape trunk, swim to the cable (reportedly with the aid of a minisub on occasion), remove the recorded tape, and then make their way back to the waiting submarine. This tape was then delivered to the NSA for processing and dissemination to the appropriate military and civilian agencies. Not long after the recovery of the first tapes, it was discovered that the Soviets felt so sure of the security of their undersea communication line, that the majority of the concersations recorded were completely uncoded! Needless to say, the eavesdropping on traffic between senior Soviet officers provided an invaluable look inside military operations in the region.
In 1981, however, this windfall came to an abrupt end when Western satellites photographed a small fleet of Russian warships gathered over the exact location of the listening device. One vessel was a unique deep salvage ship that had been monitored hurredly making its way across the globe to the site. This development caused a wave of concern through those assigned to the project, raising concerns that the operation had somehow been discovered. In what would later come to be viewed as one of the most dangerous missions of Ivy Bells, the USS Parch (SSN-683) was sent in to retrieve the next tape. Upon arrival, divers discovered that the pod had been removed. They quickly made their way back to the boat and the team exited the area, reportedly without incident.
It was clear that their fears has been well-founded. A major, but covert, investigation ended in with a startling revelation: This operation (along with at least seven other code-word operations) had been betrayed to the KGB in January 1980 by Robert Pelton, an employee of the National Security Agency for the sum of $35,000. Mr. Pelton was later convicted and sentenced to life in prison where he currently resides.
Operation Ivy Bells remains one of the most successful intelligence gathering operations in modern U.S. history, and could not have been accomplished without the daring and skill of U.S. Navy submarine officers and crew - and a handful of Navy frogmen.