Throughout the Cold War period the submarine forces of various western nations conducted numerous special operations such as harbour infiltrations,tailling etc.The thing I find hard to reconcile is did the Soviets really not realise that this was going on?The Walker family gave them access to key communications intelligence that must have given them a clue.I just find it hard to believe that this went on undetected for years.Did the Soviets try anything similar against the West?
They did. The "bells" operation, tapping a soviet undersea cable, was eventually compromised by a spy. The soviets then proceeded to play the "telephone game" with the west for various purposes; disinformation, out spies etc. Likewise the berlin tunnel operation [where the CIA dug under the soviet embassy to eavesdrop] was compromised from the start, with the soviets feeding all sorts of bs to the CIA when the berlin tunnel was completed.
The soviets had quite a bit of spies working for them, in the days when communisim was still an ideology people would take risks and die for. They infiltrated not just the US and the navy but also MI6 and allegedly MI5.
Of course mostly everything we read and hear about this comes from the people who's word you take huge grains of salt with, namely the intelligence community.