What is Russia's Poseidon nuclear drone and could it wipe out the UK in a radioactive tsunami?

A popular Russian state TV anchor has warned that Moscow could wipe Britain off the map with a nuclear tsunami in retaliation for supporting Ukraine.

In his Sunday evening primetime show on Channel One, one of the most-watched in Russia, Dmitry Kiselyov claimed on May 1 that a strike by the country’s Poseidon nuclear underwater drone could drown the UK under a 500-metre tidal wave of radioactive seawater.

Euronews Next checked his claims with three experts on nuclear weapons, submarines and drones. Here’s what we know - and don’t know - about Russia’s new nuclear torpedo and the damage it could inflict.

The Poseidon underwater drone - also known as Status-6 and in the United States as "Kanyon" - is basically a very large, nuclear-powered autonomous torpedo armed with a nuclear warhead.

What we know of it mostly stems from a 2015 leak on Russian TV of a government project for an underwater nuclear drone.

According to its mission statement, the project was focused on “damaging the important components of the adversary's economy in a coastal area and inflicting unacceptable damage to a country's territory by creating areas of wide radioactive contamination that would be unsuitable for military, economic, or other activity for long periods of time”.

In 2018, a leaked draft of the Pentagon's Nuclear Posture Review acknowledged Russia was developing a "new intercontinental, nuclear-armed, nuclear-powered, undersea autonomous torpedo”.

The torpedo, which Russia named Poseidon, is about 20 m long, can go 1,000 m deep and has a range of at least 10,000 km, Sidharth Kaushal, a research fellow for seapower and missile defence at the UK defence and security think tank RUSI, told Euronews Next.

Much of its actual capabilities remain shrouded