Key point: Russia's is working on a nuclear torpedo, but the idea may not be practical.
According to the latest Nuclear Posture Review, Russia is developing a new nuclear torpedo/drone, the Status 6. While the torpedo (also covered here by Dave Majumdar) offers some alarming new capabilities, it’s not the first such weapon that the Russians have worked on. More importantly, the Status 6 has some potentially fatal drawbacks that limit its practical effectiveness in a combat scenario.
Nuclear tipped torpedoes have considerable precedent from the Cold War. The earliest designs for the Project 627 “November”–class nuclear-attack submarines envisioned the boats acting as motherships for the T-15 nuclear torpedo, developed to attack NATO port facilities. These torpedoes offered the USSR a way of reducing NATO naval dominance, and also an alternative means of striking the United States. However, the T-15 only had a range of about twenty-five miles and a speed of thirty knots, making it difficult to envision situations in which a submarine could successfully deliver the attack. The project was cancelled, and the Novembers redesigned as normal nuclear attack subs. Later, both the United States and the Soviet Union would introduce nuclear torpedoes optimized for tactical roles.
Recommended: 5 Places World War III Could Start in 2018
Recommended: How North Korea Could Start a War