Of all the nuclear weapons in all the world, quite possibly the weirdest, most ridiculous is the nuclear torpedo which has been envisioned and developed as everything from an anti-submarine weapon to a city-ending doomsday weapon. Russia's President Vladimir Putin even claims that he's brought it back (more on that later).
After the bombs were dropped on Hiroshima and Nagasaki, the entire world realized that a new paradigm existed. It was like the morning the first Dreadnought battleship was built. Once the Dreadnought existed, every ship built before it was essentially obsolete. Same with the nuclear bombs. Your massive armored corps don't mean jack when a single bomb could've won the Battle of Kursk.
But where the construction of the Dreadnought kicked off a battleship race, the dropping of Little Boy and Fat Man kicked off a nuclear arms race. In addition to the nuclear bombs you would expect, designers in the U.S. and Soviet Union got creative, eventually creating everything from atomic cannons and recoilless rifles to atomic "mines."
Another weird weapon on that list: the nuclear torpedo. The Soviet Union was the first to investigate the concept and came up with two designs dubbed the T-5 and T-15 from 1951 to 1952. The T-5 was a sort of tactically useful weapon, fitting in standard 21-inch torpedo tubes but featuring a nuclear warhead with a 5-kiloton payload.
But the T-15 was supposed to be an absolute beast. It would require a specially modified submarine with a 61-inch diameter torpedo tube elongated to carry the weapon. Inside its shell would've been a thermonuclear warhead capable of creating a tsunami at a targeted shore, destroying the city or naval base there.
But the project was kept secret, even from the Soviet Navy, until July, 1954. When Commander-in-Chief of the Navy, Fleet Adm. Nikolai Kuznetsov, was briefed on the concept, he reportedly said, "I don't need that kind boat." One of his major sticking points: Most U.S. cities were either too well protected or too far inland for the T-15 to work.
Apparently, purpose-building a submarine with a large crew in order to carry a weapon that likely could never be used in combat is a bad idea. Who knew?
But Kuznetsov was cool with the T-5 which would fit in a standard tube. It was a new option for commanders without straining logistics or construction outside of building the weapon itself. And so the Soviets got a nuclear torpedo into testing in 1955, detonating a 3-kiloton warhead.
The weapon was primarily aimed at destroying surface ships, but was thought to be plenty capable of taking out enemy subs by compressing their hulls. One of these torpedoes was almost used during the Cuban Missile Crisis when a Russian sub was bombarded with training depth charges by U.S. destroyers trying to force it to surface.
If the nuclear torpedo had been launched, it likely would've destroyed the American warships and could've pushed the crisis into a full war.
The U.S. developed their own nuclear torpedo, the Mark 45. The Mk. 45 was designed in 1957 and first produced in 1959, though the design was tweaked in 1960. These torpedoes fit in standard tubes but had an 11-kiloton W-34 warhead on the front. They were made to travel up to 12,000 yards before being triggered by an operator.
At the moment of the blast, the weapons would crush the hulls of ships and submarines as well as crack the keels of enemy ships if detonated properly. This is like breaking a ship's back, and it drastically increases the speed at which a ship will typically sink.
Russia later developed an even more powerful nuclear torpedo. The Autonomous Special Combat Warheads boasted a 20-kiloton warhead. Luckily, neither it nor its U.S. and Russian predecessors were ever used in combat.
But, of course, Russia once bragged that it has a new nuclear torpedo, a city killer that could wipe out U.S. coastal cities and make their surrounding area radioactive for decades. It was originally announced during a speech by Putin where he bragged about a number of supposedly functional doomsday weapons.
While the hypersonic nuclear missile famously was lost in a failed launch soon after the announcement, the nuclear torpedo isn't nearly as technically challenging as the nuclear hypersonic missile.
The torpedo was called Status Six, later renamed Poseidon, and is remotely guided. So, it's basically a drone and carries a warhead of up to 100 megatons. And it has an insane range and speed, capable of being launched from 6,200 miles away and swimming at 56 knots, faster than most U.S. torpedoes. And, it's supposedly stealthy to boot, nearly undetectable.
Putin has desperately overhyped all of the weapons from that press conference, and so it's unlikely that all the braggadocio will hold up, but nuclear torpedoes are technically very feasible, and so there's no reason to think that Russia can't build and launch one. A 100-megaton warhead is pretty feasible as well. A stealthy, fast, large torpedo is pretty unlikely though.
The good news is, though, that a strategic nuclear torpedo isn't actually a game-changer, anyway. Russia has a history of overestimating U.S. missile defenses, and so they compensate by trying to create weapons that can pierce them. The nuclear torpedo is one of those, a city-killer designed to keep us from firing out city killers.
But it's just a different flavor of mutually assured destruction, similar to ballistic missile silos and nuclear missile subs or nuclear bombers. Except nuclear torpedoes are, actually, just a little weaker since they can only engage coastal cities.
So, sleep tight, unless you sleep on the water.