During the Cold War, the United States carried out an extraordinary intelligence operation to intercept communications transmitted through an underwater cable used by the Soviet Navy. Instead of relying on satellites or conventional surveillance methods, American intelligence agencies sent submarines and divers to the ocean floor. Their target was a deep-sea communication cable carrying sensitive Soviet military information. Known as Operation Ivy Bells, the mission became one of the most remarkable examples of underwater espionage in modern intelligence history. The operation was a joint initiative involving the Central Intelligence Agency (CIA), the U.S. Navy, and the National Security Agency (NSA), this operation took place in the Sea of Okhotsk, near the Kamchatka Peninsula. Its primary objective was to intercept Soviet naval communications and gather intelligence about submarine operations, military movements, nuclear capabilities, and weapons development. However, the highly classified mission eventually collapsed after a former NSA employee leaked its secrets to the Soviet Union.How the American underwater surveillance operation workedThe idea behind Operation Ivy Bells emerged in 1971. Captain James Bradley, an intelligence specialist with the Office of Naval Intelligence, suspected that the Soviet Union had installed an underwater telephone cable connecting Vladivostok with its Pacific Fleet base in Petropavlovsk. In 1972, the USS Halibut, commanded by Jack McNish, was dispatched to locate the cable. After several days of searching the seabed, the American team successfully identified its location. Investigators reportedly noticed restrictions prohibiting ships from dropping anchors in the surrounding area, which helped them identify the cable’s position.Three U.S. Navy divers descended to the seabed to install a specialized listening device. They cleared away surrounding debris and attached the equipment without cutting or damaging the communication cable. Later, Bell Labs developed improved technology for the surveillance system. The upgraded device was approximately 20 foot long and capable of recording intercepted communications for later examination. American divers returned roughly once a month to retrieve the recordings and deliver them to the NSA for analysis. The intelligence collected provided valuable insights into Soviet naval strategies, military movements, nuclear-powered submarines, and missile technology. The information reportedly strengthened American intelligence capabilities during the Cold War and provided useful material ahead of the 1979 SALT II treaty negotiations.A former NSA employee’s betrayal exposed a decade of espionageFor nearly ten years, the Soviet Union remained unaware of Operation Ivy Bells. However, in 1981, satellite imagery revealed military vessels and a salvage ship near the underwater cable. The American submarine USS Parche later discovered that the listening device had been removed. Investigations identified Ronald Pelton, a former National Security Agency (NSA) employee, as the source of the security breach. Facing serious financial difficulties and bankruptcy, Pelton contacted the Soviet Embassy in Washington, D.C., in 1980 and sold classified American intelligence. He reportedly received $5,000 initially for information about Operation Ivy Bells, followed by another $30,000.His disclosures enabled the KGB to locate and recover the surveillance equipment. A KGB defector helped expose Pelton in 1985, and he subsequently confessed during an FBI interrogation. He received three life sentences, served approximately 30 years in prison, and was released in 2015. He died in 2022 at age 80. The recovered device was later displayed at Moscow’s Armed Forces Museum with a plaque reading, “Property of the Government of the United States of America.” The operation’s downfall highlighted the vulnerability of sophisticated intelligence missions to human betrayal.