North Korea’s Latest Nuclear Asset: Why the ‘Tsunami’ Underwater Drone May Be its Most Devastating Yet

Among a wide range of assets designed to deliver nuclear weapons which have seen intensive recent testing in North Korea, the Haeil-2 underwater drone saw its second round of tests commence from April 4-6, during which it simulated a 1000km journey at sea over 71 hours. The drone’s existence was only announced earlier in the year, but it has reportedly been under development since 2012 three years after the country carried out its first controlled nuclear detonation. North Korea has been developing nuclear weapons since the late 1980s, and according to U.S. intelligence it likely had a limited nuclear strike capability in the early 1990s. This has expanded tremendously since with the testing of miniaturised warheads and a range of delivery vehicles ranging from intercontinental range ballistic missiles to hypersonic glide vehicles. Haeil-2 translates to “tsunami” in Korean, and reportedly operates by detonating nuclear warheads below sea to trigger a radioactive tsunami against enemy coasts. When first tested in March state media announced regarding its role: “This nuclear underwater attack drone can be deployed at any coast and port or towed by a surface ship for operation… The system will serve as an advantageous and prospective military potential of the armed forces of the [Democratic People’s Republic of Korea] essential for containing all evolving military actions of enemies, removing threats and defending the country.” 

State media reported regarding the latest test of the Haeil-2 drone: “the test warhead accurately detonated underwater. The test perfectly proved the reliability of the underwater strategic weapon system and its fatal attack ability.” Serving both to advance the drone program and as a show of force, the test comes as South Korea and the United States launch major war games which include simulated offensives into North Korean territory. Pyongyang has consistently responded to such exercises with significant weapons tests. As the country has expanded its production of nuclear warheads, the Haeil-2 drone provides an asset with few counterparts elsewhere in the world which could seriously complicate U.S. and allied plans to intercept North Korean nuclear attacks. Tsunami-triggering nuclear assets were first conceived in the Soviet Union in the 1950s, namely under the Lavina program, although this was never operationalised. Such attacks are far more difficult to detect or intercept than those by ballistic missiles, and the Haeil-2’s capabilities are thus highly complementary to those of North Korea’s increasingly diverse and survivable ballistic and cruise missile arsenals also designed for nuclear delivery. The East Asian state has also moved ahead with developing a submarine launched cruise missile capability which could help to hold U.S. military targets across much of East Asia at risk, with a landmark test for these assets carried out in March.

Although lacking any meaningful known aerial delivery capability for its nuclear weapons, a growing naval nuclear delivery capability has strengthened North Korea’s deterrent considerably since the mid 2010s with its strategic submarine arsenal only expected to continue to grow. It remains likely that a means of operating assets like the Haeil-2 in the Eastern Pacific in range to strike the United States mainland will be pursued, complementing the increasingly long range of the North Korean ballistic missile submarine arsenal. The ability to strike the U.S. mainland has long been highly prized by Pyongyang, which remains in a state of war with Washington, since the U.S. has considered large scale attacks including major nuclear strikes against it on multiple occasions. President Barak Obama favoured an attack in 2016, and was reportedly deterred only by to severe warnings from the Pentagon, while his successor Donald Trump in 2017 drew up plans for mass nuclear attacks which were expected to kill millions of Koreans. The unprovoked strikes were on both occasions deterred largely by North Korean retaliatory capabilities and the Pentagon’s lack of intelligence on the locations of its leadership and weapons stockpiles. 

Previously the Harry Truman, Dwight Eisenhower and Richard Nixon administrations all very seriously considered nuclear attacks on the East Asian country, while the Lyndon Johnson and Bill Clinton administrations came very close to launching non nuclear attacks. North Korea has yet to complete the clean up of American munitions from the previous U.S.-led Western bombing campaign during the Korean War, which killed the bulk of the 20-30 percent of its population that died during the three year conflict. With the memory of the Korean War being a key driver of North Korean security policy in the face of a perceived serious threat from the United States, which has only been reinforced by unprovoked American attacks against Libya and Iraq which  both surrendered their missile deterrents and weapons of mass destruction, development of nuclear delivery assets like the Haeil is expected to continue.