Through John Walker's spy ring and the subsequent capture of the USS Pueblo, a small american trawler, rigged with secret ELINT equipment, the soviets could from then on secretly intercept, decrypt and decodify any US Navy communication.
After the K-129, a Soviet Ballistic Missile Diesel Sub sunk in the middle of the Pacific Ocean, the Soviets quickly blamed on the US. Also, a not too long after, the USS Seawolf returned to port, covertly at night, with a destroyed and almost torn apart sail.
A few months after, the USS Scorpion sunk while returning to home port, about a day after having been diverted from its original and most direct course home, to investigate a mysterious Soviet naval exercise, involving ships which wouldnt operate together as a normal practice.
Both navies hold together a pact of secrecy regarding these episodes.
__________________
|