"The US saw Russia moving to possibly test Putin's nuclear-powered 'doomsday' torpedo"

Russian efforts to test a one-of-a-kind nuclear-powered torpedo prototype may have hit a snag, a US official told CNN on Thursday.

Unveiled by Russian President Vladimir Putin in 2018, the self-propelled torpedo, or unmanned underwater vehicle, is claimed to have an unlimited range and the ability to carry a nuclear warhead up to 125 times as powerful as the bomb dropped on Hiroshima, according to Popular Mechanics.

"Unmanned underwater vehicles can carry either conventional or nuclear warheads, which enables them to engage various targets, including aircraft groups, coastal fortifications, and infrastructure," Putin said at the time, claiming it was invulnerable to counter-measures. "There is simply nothing in the world capable of withstanding them."

All types of torpedoes are essentially unstoppable. But they are limited by the range and speed challenges of moving a heavy object through water, which is much higher friction than air. Russia's claims to use nuclear power to propel Poseidon potentially solve this in an unprecedented way — if it actually works...

In 2019, Russia's defense ministry released a video appearing to show an underwater test of the system, which some have labeled a "doomsday" device because of its huge potential payload and theoretical ability to generate a radioactive tsunami that could sweep across coastal cities.