Kim Jong Un Tests Undersea Drone, Warns of 'Radioactive Tsunami'

North Korean leader Kim Jong Un oversaw tests of weapons designed to deliver nuclear strikes against the US and its allies, including one his regime billed as a new underwater drone that can create a "radioactive tsunami."

The tests from Tuesday through Thursday also included cruise missiles that were affixed with mock nuclear warheads, the official Korean Central News Agency reported Friday. The underwater drone cruised for nearly 60 hours off its east coast before detonating, it said.

"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," KCNA said.

While this was the first mention that North Korea's propaganda apparatus has made of such a drone being deployed, the state has numerous mini submarines that rely on antiquated technology and are relatively easy to spot in open waters if they stray far from the coast.

The drills represent the latest efforts by North Korea to enhance its ability to deliver a credible nuclear strike against the US and its main allies in Asia — South Korea and Japan. This has included developing new solid-fuel ballistic missiles that are quick to deploy and maneuverable in flight, as well as new devices to deliver warheads.

North Korea has warned the US of an unprecedented response to joint military exercises with South Korea and threatened to turn the Pacific Ocean into its "firing range" if the drills continue.

The latest tests of nuclear strike capabilities coincided with the end of one of the biggest US-South Korean joint drills in years. In June, Seoul and Washington are planning to conduct their largest-ever live-fire exercises, which could lead to more provocations from Pyongyang.

KCNA said Kim bitterly criticized "the U.S. imperialists for desperately resorting to military moves imperiling the regional situation under the pretense of fulfilling their commitment to defending allies." The US and its allies said the drills are needed to prepare for the threats posed by Pyongyang as it advances its atomic weapons arsenal.

The joint drills had been scaled down or halted under former President Donald Trump, who was hoping the move would facilitate his nuclear negotiations with the North Korean leader. Those talks led to no concrete steps to wind down Kim's nuclear arsenal, which only grew larger as the talks sputtered.

Kim emphasized the importance of maintaining a strong nuclear defense capability and underscored the need for the country to continuously develop its nuclear weapons program to protect its people and territory from perceived threats, particularly from the US and South Korea, KCNA said.