North Korea's showing off an underwater nuclear attack drone it says can cause a 'radioactive tsunami,' but the threat is likely 'exaggerated'

• North Korea has tested an underwater nuclear attack drone, similar to Russia's Poseidon torpedo.
• Pyongyang claims the weapon could cause "radioactive tsunamis," but it has been met with skepticism.

North Korea has released new imagery of testing of what it claims is an underwater nuclear attack drone that can be deployed to devastating effect, but officials and expert observers believe Pyongyang's claims to be "exaggerated."

Pyongyang first tested the weapon last week after over a decade of development, sending it cruising off the country's eastern coast at a depth of up to nearly 500 feet for around 60 hours. State media said that a test warhead detonated underwater and hailed the mission as a success because it "fully confirmed" the weapon's capabilities.

"The mission of the underwater nuclear strategic weapon is to stealthily infiltrate into operational waters and make a super-scale radioactive tsunami through underwater explosion to destroy naval striker groups and major operational ports of the enemy," state-run media outlet KCNA said.

"This nuclear underwater attack drone can be deployed at any coast and port or towed by a surface ship for operation," state media boasted.

Another round of testing for the drone — named "Haeil-1" — was conducted over the weekend, and that time, the North Korean device traveled over 370 miles for more than 41 hours, state media reported, adding that the test warhead was "correctly set off."

The recent testing marks the first time that North Korea has publicly revealed this type of potential weapon, which seems to resemble a similar device in development by another isolated government — Russia.

For years, Moscow has been working on a intercontinental autonomous nuclear torpedo, sometimes referred to as a drone, called the Poseidon. That weapon has been described as a "doomsday" device because it has been speculated that the payload could potentially cause a radioactive tsunami, as Pyongyang claims its weapon can do.

But like Poseidon, rumors of the Haeil drone's capabilities have potentially been exaggerated, and there's no guarantee that it will even work. North Korea's claims about the weapon have already been met with by skepticism by experts and officials.

South Korea's Joint Chiefs of Staff (JCS) expressed its doubts about the weapon and said its military believes that it is "highly likely" Pyongyang's claims "are exaggerated and manipulated," according to Seoul-based NK News.

"There have been signs that North Korea has been developing unmanned submarines, but we assess that they are still at an elementary level," South Korea's JCS added.

Ankit Panda, a senior fellow in the nuclear policy program at the Carnegie Endowment for International Peace, also questioned the weapon's future. "There are good reasons to maintain skepticism that North Korea will widely produce or deploy the Haeil system," he wrote in an NK Pro analysis.

That said, Panda noted in an interview with CNN that "there's nothing preventing North Korea from, in principle, putting a nuclear device on an underwater vehicle like this and detonating it," but a lot of questions remain about how it works and what this system is actually capable of compared to the claims of North Korean state media.

North Korea's recent underwater drone testing — which came in tandem with the launch of several strategic cruise missiles — comes on the heels of extensive military drills by the US and South Korea, often regarded by Pyongyang as provocative, and as the country continues to advance its weapons programs.

Earlier this month, Pyongyang tested the Hwasong-17 — its largest intercontinental ballistic missile yet — which reached a maximum altitude of over 3,700 miles and flew over 620 miles off the coast of the Korean peninsula. It was one of several missile launches that took place this month.

North Korean leader Kim Jong Un this week urged scientists to bolster production of weapons-grade nuclear material and work on expanding his country's nuclear arsenal "exponentially," according to a KCNA report, which added that Kim placed "important tasks" — which were not immediately identified — on Pyongyang's weapons industry.

Meanwhile, the country on Tuesday unveiled photos of Kim inspecting new and smaller nuclear warheads, which experts speculate could be fitted on various types of delivery systems.

Despite international pressure to halt its weapons development programs, particularly its nuclear programs, North Korea effectively declared in September of last year that its nuclear course is irreversible.