North Korea performed its first underwater-launched missile tests in nearly three years, likely from an as-yet-deployed submarine that it says is designed to launch nuclear weapons.
The high-profile tests come as North Korea is dialling up weapons demonstrations in an apparent bid to pressure the United States to offer greater concessions if it wants a resumption of diplomacy.
The official Korean Central News Agency said the military tested two types of strategic cruise missiles in the country’s eastern waters. It said the tests were aimed at assessing the readiness of North Korea’s underwater combat systems and demonstrating the reliability of its nuclear deterrent.
KCNA didn’t say what launch platform was used, but the agency’s photos of the launch suggested the country mobilised the “Hero Kim Kun Ok” submarine that was unveiled in 2023 with great fanfare but drew outside scepticism about its claimed capabilities.
If confirmed, the missile launches were the first public weapons tests from that submarine, which implies North Korea began testing weapons systems for the vessel before its deployment in what would be a major threat to South Korea and the US, experts say.
North Korea for years has been developing various missiles designed to be fired from underwater, which was a worrying development for its rivals because such launches would be difficult to detect in advance.
Before Wednesday’s tests, all North Korean underwater launches were made from a 2,000-ton-class submarine with a single launch tube. Many experts call it a test platform rather than an operational submarine in active service.
In September 2023, North Korea launched the “Hero Kim Kun Ok”, saying the submarine was capable of launching tactical nuclear weapons from underwater. State media photos showed the submarine has at least 10 missile launch tubes in addition to its torpedo tubes.
At the time, many foreign experts were sceptical the submarine would work as North Korea described, saying it was likely a modification of an existing, ageing diesel-fuelled submarine.
A lack of known weapons tests from the submarine in the past three years signalled it had some technical issues, including an ability to right itself. But Wednesday’s tests indicated North Korea had resolved those issues and started testing the weapons to be carried by the submarine, according to analyst Shin Jong-woo at South Korea’s Defence and Security Forum.
North Korea will likely also test ballistic missiles from the submarine before it is deployed by the navy, Shin said.
The submarine’s deployment “would pose a significant threat” to South Korea and the US because underwater-launched missiles are “formidable weapons that we don’t know when and where they would be fired,” said Moon Keun-sik, a submarine expert who teaches at Seoul’s Hanyang University.
South Korea’s Joint Chiefs of Staff said it detected the launches and concluded the missiles were launched from a submarine, with one fired from a vertical launch tube and the other from a torpedo tube. The South’s military didn’t immediately specify the North Korean submarine that it believed was involved.North Korean leader Kim Jong Un recently turned his focus to strengthening the navy after a decade of expanding the country’s ballistic missile program. In March 2025, North Korea unveiled its first nuclear-powered submarine under construction, but it’s unclear when the construction would be completed.
Wednesday’s launches were the first underwater testing activities since January 2024. They extended a recent run in weapons demonstrations, including tests of various hypersonic missile systems on September 20 and October 3 that the North said were aimed at advancing its arsenal of weapons designed to overwhelm missile defences in South Korea and Japan.
The tests came after North Korea in August rebuffed US President Donald Trump’s apparent effort to revive diplomacy with Mr Kim by scaling back a military drill with South Korea. North Korea said shortening the duration of the drill won’t change its hostile nature.
North Korea has previously said it could return to diplomacy if the US abandons its “hostile” policy toward Pyongyang and drops demands for the North’s denuclearisation as a precondition for talks.
North Korea’s latest submarine-launched tests were part its efforts to gain leverage in potential negotiations with the US, Moon said.
“North Korea would want to say it would never give up its nukes,” Mr Moon said. “It’s sending a message to the US, saying that ‘We’ve perfected land-abased nuclear weapons and are deploying nuclear weapons to the maritime domain so that you shouldn’t demand our denuclearisation any longer’.”