North Korea test-fires two submarine-launched cruise missiles, likely from new attack sub

North Korea said on 15 October that its Missile Administration had test-fired two types of submarine-launched strategic cruise missiles in the East Sea, also known as the Sea of Japan, the previous day. South Korean experts assess that the missiles were fired from the Hero Kim Kun Ok, a 3,000-tonne-class boat that Pyongyang unveiled in September 2023 as its first tactical nuclear attack submarine. If confirmed, it would be the first missile launch from that vessel.

According to North Korean state media, as reported by Yonhap and Jiji Press, the test was meant to examine the mobilised posture of the navy's underwater combat systems and to demonstrate the reliability of the country's war deterrent. Pyongyang uses the word strategic to signal nuclear capability. The firing was overseen by Kim Jong-sik, a member of the ruling party's Central Military Commission, and Jang Chang-ha, director-general of the Missile Administration, together with navy underwater weapons engineers. Leader Kim Jong-un did not attend.

State media claimed the launch had no adverse impact on the security of neighbouring countries, but it disclosed neither flight times nor ranges. That claim could not be independently verified.

Seoul says it tracked the launches

South Korea's Joint Chiefs of Staff did not announce the launch when it happened. On 15 October its spokesperson, Captain Jang Do-young, said the military had monitored and tracked the missiles from before launch through the cruise phase to the end of their flight, rejecting suggestions that they had been missed. He declined to name the surveillance assets involved, citing confidentiality with the United States, but said one type was fired from a vertical launching system and the other from a torpedo tube. Japan had not issued its own statement, USNI News reported.

Because cruise missiles usually fly at around 100 metres, the JoongAng Daily noted, the early detection appears to have relied on sensors other than the radars used to track ballistic missiles.

First armed outing for the Hero Kim Kun Ok

North Korea last disclosed a submarine-launched cruise missile firing in January 2024, when Pulhwasal-3-31 missiles were launched from the older 2,000-tonne 8.24 Yongung. The Hero Kim Kun Ok, hull number 841, is the only boat of its class built so far, and in March 2025 the North released photographs of a nuclear-powered ballistic missile submarine under construction. At the 2023 launch ceremony, Kim Jong-un said arming the navy with nuclear weapons could not be delayed any further.

Shin Jong-woo of the Korea Defense Security Forum told the JoongAng Daily the North appears to be testing combat systems to bring the submarine into service and will probably follow with submarine-launched ballistic missile tests. Hong Min of the Korea Institute for National Unification said firing two missile types with different ranges, speeds and approach paths at staggered intervals would force air defences to deal with threats from several directions at once. Some analysts suggested the pair were a Hwasal-2 and a Pulhwasal-3-31. The latter has a reported range of up to 2,000 kilometres and is thought to carry the Hwasan-31 tactical nuclear warhead, putting the whole Korean Peninsula and US bases in Japan within reach.

Second launch in three days

The test came two days after North Korea fired ballistic missiles from the Pyongyang area on 12 October, one of which flew more than 900 kilometres, according to Japan's Joint Staff. Japan's vice defence minister, Takashi Koyari, said the North had launched at least 18 ballistic missiles and other projectiles on 11 occasions this year. Pyongyang said that test confirmed a technical upgrade to an important core element of its weapons.

The JoongAng Daily said the attendance of working-level officials rather than Kim may signal a shift from weapons development towards routine operational use. A nuclear-capable cruise missile that can be fired from a submerged boat adds a low-flying threat that US and Japanese forces, including those based in Japan who would matter in any wider regional crisis, will need to plan around.