North Korea has released new images showing what it says is its first nuclear-powered submarine.

The pictures, published on Thursday by the Korean Central News Agency (KCNA), show leader Kim Jong Un inspecting a large submarine hull inside an indoor facility. The vessel has not yet been launched.

State media said the submarine weighs around 8,700 tons, similar in size to some U.S. nuclear-powered attack submarines.

North Korea has described it as a “strategic guided missile submarine” or a “strategic nuclear attack submarine,” suggesting it is designed to carry nuclear weapons.

Earlier photos of the submarine only showed parts of the hull. The latest images show the full hull, which appears largely complete. Experts say this usually means most internal systems, including possibly the nuclear reactor, are already installed.

Moon Keun-sik, a submarine expert at Hanyang University in Seoul, said the submarine could be ready for sea trials within months. Hong Min, a senior researcher at the Korea Institute for National Unification, suggested missile tests could happen within two years.

Nuclear-powered submarines can stay underwater for long periods, are usually faster, and quieter than conventional submarines. Currently, only the United States, China, Russia, France, and the United Kingdom, operate such vessels.

Kim first announced plans for nuclear submarines in 2021 as part of a five-year military development programme. That plan also includes intercontinental ballistic missiles, hypersonic weapons, reconnaissance satellites, and advanced naval ships. Since then, North Korea has carried out several missile tests to develop these systems.

During the inspection, Kim highlighted the submarine’s importance for North Korea’s defence strategy, calling it a way to strengthen the country’s offensive and defensive capabilities.

He also criticised South Korea’s plans to build nuclear-powered submarines with U.S. support, describing them as a direct threat to North Korea’s security and maritime sovereignty.

Analysts say North Korea’s own actions have contributed to regional tensions. Leif-Eric Easley, a professor at Ewha Womans University, said Pyongyang’s rejection of diplomacy, threats with nuclear weapons, and focus on military development at the expense of economic welfare have fuelled the arms race.

Despite progress, experts say North Korea’s navy is still weaker than South Korea’s, which has advanced guided-missile destroyers and modern conventional submarines.

North Korea also faced setbacks this year when one of its newly built guided-missile destroyers capsized during launch but was later repaired.

KCNA also criticised the arrival of a U.S. nuclear-powered submarine at a South Korean port, calling it a move that increases military tensions.

KCNA reported that Kim received a message from Russian President Vladimir Putin on 18 December praising North Korean soldiers’ participation in the Ukraine war and describing 2025 as a year of special importance for Moscow-Pyongyang relations.

The images also showed Kim accompanied by his daughter, Kim Ju Ae, whose growing public appearances have led to speculation about her future role in the regime.

References: CNN, NYTimes