UAV event in South Hamgyong, Hongwŏn area, Korea, Democratic People's Republic of on Fri 24th March 2023

North Korea has tested a new underwater attack drone that can generate a radioactive tsunami, the country's state media has claimed.

The nuclear-capable drone was launched this week off the coast of Riwon County in South Hamgyong Province.

It reached its target off Hongwon Bay, where it detonated its test warhead, according to the Korean Central News Agency (KCNA), having cruised underwater for more than 59 hours at a depth of 80 to 150m.

The drone is called Unmanned Underwater Nuclear Attack Craft 'Haeil'. Haeil means tsunami.

It is made to sneak up on enemy naval fleets and ports before producing an underwater explosion that creates a radioactive wave.

The test "verified [the drone's] reliability" and "confirmed its lethal strike capability", KCNA said.

Four "strategic cruise missiles" were also tested, flying for more than two hours over the sea. 

"The respected comrade Kim Jong Un was greatly satisfied with the results," KCNA said.

It comes as the US and South Korea completed an 11-day exercise that included major field training, and as the US reportedly prepared to send an aircraft carrier to the area for more military drills.

North Korea described the exercises as "intentional, persistent and provocative" and said they had pushed it to "an irreversibly dangerous point".

It described the US as "imperialists" and South Korea as a "puppet regime of traitors", saying that the two countries had "kicked off a large-scale dangerous drill, an actual drill for occupying the DPRK".

South Korean defence minister Lee Jong-Sup said on Thursday that the North was unlikely to have mastered the technology to arm its most advanced weapons, although it had made "significant progress".

Leif-Eric Easley, a professor at Ewha University in Seoul, said: "Pyongyang's latest claim to have a nuclear-capable underwater drone should be met with scepticism.

"But it is clearly intended to show that the Kim regime has so many different means of nuclear attack that any pre-emptive or decapitation strike against it would fail disastrously."

North Korea has fired more than 20 ballistic and cruise missiles this year, following a record of more than 70 fired last year.

Mr Kim wants to negotiate relief from Western sanctions but refuses to agree to US demands for the curtailment of his nuclear programme first, saying this is necessary for the North to defend itself.