North Korea claims it can trigger ‘radioactive tsunamis’ with new nuclear-capable underwater drone

North Korea says it has tested a nuclear-capable underwater drone that can set off a “super-scale radioactive tsunami" to decimate naval fleets and ports of the enemy.

The objective of the "secret weapon" is to infiltrate enemy waters and create an underwater explosion that will trigger tsunami waves, destroying naval strike groups and coastline targets including major ports, the state news agency KCNA said on Friday.

And while Pyongyang’s latest claims were met with scepticism by defence experts, they underline the Kim Jong-un regime’s commitment to developing a range of means to carry out a nuclear attack.

North Korea said it conducted the tests from 21-23 March, deploying it off the coast of Riwon County of South Hamgyong Province on Tuesday.

The drone cruised for over 59 hours, forming oval and figure-of-eight patterns at a depth of 80 to 150 metres, it said.

It was detonated under a mock enemy port off Hongwon Bay between the east coast cities of Hamhung and Sinpho.

The test “verified its reliability and safety and fully confirmed its lethal strike capability,” according to KCNA.

This is the first time North Korea has made claims about developing the underwater stealth weapon, saying it began the development of the weapon system in 2012.

In total, KCNA claimed that Mr Kim oversaw 29 tests of the weapon, which has been named the "Unmanned Underwater Nuclear Attack Craft ‘Haeil’” – a Korean word meaning tidal waves or tsunamis.

The first pictures published in the country’s official Rodong Sinmun newspaper showed Mr Kim admiringly looking at a large torpedo-shaped object at an unspecified indoor facility.

Another picture purportedly showed an underwater explosion triggering a huge pillar of water that exploded up into the air, and a third showed an object moving below the ocean’s surface.

North Korea said the tests were aimed at alerting the US and allies to a brewing “nuclear crisis” as they continue with their “intentional, persistent and provocative war drills.”

Leif-Eric Easley, a professor at Ewha University in Seoul, said Pyongyang’s claims about the new underwater drone weapon system “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 preemptive or decapitation strike against it would fail disastrously.”

Ankit Panda, a nuclear weapons specialist at the Carnegie Endowment for International Peace, also raised questions over the North’s claims.

“I tend to take North Korea seriously, but can’t rule out the possibility that this is an attempt at deception/psyop ((psychological operations).”

“This un-crewed underwater vehicle will be vulnerable to anti-submarine warfare capabilities if it were to deploy beyond North Korea‘s coastal waters. It will also be susceptible to preemptive strikes when in port,” said Mr Panda.

The three-day-long exercises overseen by Mr Kim also included launches of four cruise missiles “tipped with a test warhead simulating a nuclear warhead” on Wednesday.

North Korean military launched two “Hwasal-1”-type strategic cruise missiles and two “Hwasal-2”-type strategic cruise missiles from four different locations.

The missiles “accurately hit the target set in the East Sea of Korea after flying... distance[s] of 1500km and 1800km,” state media said.

It said the drill “verified once again the operational reliability of nuclear explosion control devices and detonators by applying the mid-air-explosion (600 meters above the target) strike mode to two different missiles”.

Tensions are high in the Korean peninsula with the US ramping up its military presence and drills in the region alongside allies South Korea and Japan, accelerating a cycle of tit-for-tat responses.

The US and South Korea finished an 11-day exercise that included their biggest field training in years on Thursday and are preparing another round of joint naval drills that will reportedly involve a US aircraft carrier.

The US is reportedly planning to deploy aircraft carrier strike groups and other advanced assets to waters off the Korean Peninsula, which is expected to spark a reaction from Pyongyang.

On Friday, the South Korean president – who has pledged a hardline approach toward the North – vowed to make Pyongyang pay for its “reckless provocations” as he attended a remembrance service honouring 55 South Korean troops killed during major clashes with the North near their western sea border in recent years.

Yoon Suk-yeol said North Korea is “advancing its nuclear weapons by the day, and carrying out missile provocations with an unprecedented intensity” during the West Sea Defence Day.

North Korea has fired over 20 ballistic and cruise missiles across 10 launch events this year, including the test of an intercontinental ballistic missile last Thursday.