Próby [skuteczne] na Morzu Ochockim, 1971r. [ang.]
Something like this had been done before. In 1971, the American intelligence community learned from still undisclosed sources that two important units of the Russian Navy were communicating via an undersea cable buried in the Sea of Okhotsk, on Russia’s Far East Coast. The cable linked a regional Navy command to the mainland headquarters at Vladivostok.
A hand-picked team of Central Intelligence Agency and National Security Agency operatives was assembled somewhere in the Washington area, under deep cover, and worked out a plan, using Navy divers, modified submarines and a deep-submarine rescue vehicle, that succeeded, after much trial and error, in locating the Russian cable. The divers planted a sophisticated listening device on the cable that successfully intercepted the Russian traffic and recorded it on a taping system.
The NSA learned that senior Russian navy officers, convinced of the security of their communication link, chatted away with their peers without encryption. The recording device and its tape had to be replaced monthly and the project rolled on merrily for a decade until it was compromised by a forty-four-year-old civilian NSA technician named Ronald Pelton who was fluent in Russian. Pelton was betrayed by a Russian defector in 1985 and sentenced to prison. He was paid just $5,000 by the Russians for his revelations about the operation, along with $35,000 for other Russian operational data he provided that was never made public.
That underwater success, codenamed Ivy Bells, was innovative and risky, and produced invaluable intelligence about the Russian Navy’s intentions and planning.