Installation
Despite these obstacles, the potential for an intelligence coup was too great to ignore, and in October 1971 the United States sent the purpose-modified submarine USS Halibut (SSGN-587) deep into the Sea of Okhotsk. Divers working from the Halibut found the cable in 400 ft (120 m) of water and installed a 20 ft (6.1 m) long device, which wrapped around the cable without piercing its casing and recorded all communications made over it. The large recording device was designed to detach if the cable was raised for repair.
The tapping of the Soviet naval cable was so secret that most sailors involved did not have the security clearance needed to know about it. A cover story was thus created to disguise the actual mission: It was claimed that the spy submarines were sent to the Soviet naval range in the Sea of Okhotsk to recover the Soviet SS-N-12 Sandbox supersonic anti-ship missile (AShM) debris so that countermeasures could be developed.
Although created as a cover story, this mission was actually carried out with great success: U.S. Navy divers recovered all of the SS-N-12 debris, with the largest debris no larger than 6 inches, and a total of more than 2 million pieces. The debris were taken back to the U.S. and the U.S. Naval Research Laboratory reconstructed the AShM based on these pieces, and at least one sample was also reverse engineered. They discovered that the SS-N-12 AShM was guided by radar only, and the infrared (IR) guidance previously suspected did not exist. From the samples built, countermeasures were successfully developed and deployed.
Read more about this topic: Operation Ivy Bells