North Korea Says It’s Building a Nuclear-Powered Submarine

The announcement came amid fears that Pyongyang may be receiving crucial military technology from Russia in return for sending troops and weapons for its war against Ukraine.

North Korea said on Saturday that it was building its first nuclear-powered submarine to enhance its nuclear weapons abilities, and the state news media showed the nation’s leader, Kim Jong-un, inspecting part of what appeared to be a new submarine larger than any owned by the country.

The announcement, made in the state news media, came as United States and South Korean officials feared that the North may be receiving technological help from Russia to help modernize its military in return for sending troops and conventional weapons to help in its war against Ukraine.

Mr. Kim “learned about the building of a nuclear-powered strategic guided missile submarine,” the North’s official Korean Central News Agency said in a report on Saturday about his visit to an unidentified naval shipyard. The agency carried photographs showing what appeared to be the hull of a submarine under construction.

It was the first time that North Korea claimed that a nuclear-powered submarine was under construction and claimed to show a photograph of it.

North Korea has dozens of old Soviet-era submarines, all diesel-powered, which would have to resurface frequently to recharge their batteries during a long-distance trip like crossing the Pacific. A nuclear-powered submarine, which can cover a long distance without resurfacing, would enhance North Korea’s ability to approach a faraway enemy like the United States without being detected, and to strike it with nuclear missiles.

The state news media on Saturday quoted Mr. Kim as saying that his country’s naval might would be “fully displayed in any necessary waters without limitation.”

North Korea has vowed to try to build a nuclear-powered submarine since Mr. Kim designated it as one of his top military priorities in his ruling Workers’ Party meeting in 2021.

Outside analysts have doubted that North Korea has technical and engineering capabilities to build a nuclear submarine, including a small nuclear reactor that would propel the vessel. But Mr. Kim’s submarine project may get a boost if Russia helps North Korea clear technological hurdles in return for the thousands of troops and large shipments of artillery shells and missiles that it sent to aid Russia’s war against Ukraine, said Yang Moo-jin, the president of the University of North Korean Studies in Seoul.

North Korea’s old submarines can be used to carry spies to South Korea or launch torpedoes. The United States and its allies have closely watched the North’s attempts to develop a missile-launching sub since the country began testing missiles designed for submarines about a decade ago.

In 2023, North Korea announce​d the completion of a “tactical nuclear attack submarine.” It was a remodeled Soviet-era diesel-powered vessel that it said was capable of launching nuclear missiles. But South Korea’s military expressed skepticism about the vessel’s abnormal design, saying that it did not look capable of normal operation. There has been no evidence that North Korea has test-launched a missile from the vessel.

The newly unveiled submarine appeared to be larger than the 2023 model, said Hong Min, an expert on the North Korean military at the Korea Institute for National Unification in Seoul.

Although little is known about the new vessel, the name “nuclear-powered strategic guided missile submarine” suggests that it was designed to launch both nuclear ballistic and cruise missiles that the North has been developing, Mr. Hong said.