North Korea released new images to state media on Thursday suggesting major progress in its nuclear-powered submarine program, a development that could significantly reshape security dynamics on the Korean Peninsula.

The photos, published by the Korean Central News Agency (KCNA), show host Kim Jong Un inspecting what appears to be a nearly completed submarine hull during a visit to a shipyard.

The revelation comes as Kim sharply criticizes South Korea’s own plans to develop nuclear-powered submarines, calling them a direct threat to the North.

Images show an advanced stage of construction

KCNA said the leader inspected the construction of what North Korea describes as an 8,700-ton nuclear-powered submarine. The ship has previously been described by the regime as a “strategic missile submarine” or a “strategic nuclear attack submarine,” indicating that it is intended to carry nuclear weapons.

The project has been touted as a central part of its efforts to modernize and nuclear-arm the country’s navy.

The agency did not say when the inspection took place, but released images show the executive walking next to a massive burgundy-colored ship inside a meeting room. The hull appears to be coated with anti-corrosion paint and largely finished. Senior officials accompanied him and his daughter.

This is the first time since March that North Korean media have published images of the submarine, with previous photos showing only partial lower sections of the hull.

Experts assess launch schedule and capabilities

It is still unclear how operationally ready the submarine is. Still, experts say the images suggest substantial progress. Submarines are typically built from the inside out, meaning that a completed hull often indicates that major internal systems are already installed.

“Showing the ship in its entirety seems to indicate that most of the equipment has already been installed and it is about to be launched,” said Moon Keun-sik, a submarine expert at Hanyang University in Seoul.

He further added that the vessel could possibly be tested at sea within a few months.

A nuclear-powered submarine would give North Korea a greater ability to launch missiles from water, a capability that is difficult to detect in advance. This constitutes a major concern for regional security planners, although doubts remain about the heavily sanctioned country’s ability to fully support such a complex system.

Kim links project to regional rivalry

During the visit to the shipyard, the North Korean leader condemned South Korea’s pursuit of nuclear-powered submarine technology, an effort supported by U.S. President Donald Trump. He called the South Korean push an “offensive act” that seriously undermines North Korea’s security and maritime sovereignty.

He argued that Seoul’s plans only reinforce the need for Pyongyang to strengthen its own naval forces. He said the completion of the submarine would be a “historic” step in strengthening the country’s nuclear deterrent against what he called enemy threats.

A nuclear-powered submarine was first listed in 2021 as part of a broader weapons development plan. This list also included solid-fuel intercontinental ballistic missiles, hypersonic weapons, reconnaissance satellites and missiles with multiple warheads. Since then, North Korea has conducted a series of tests aimed at advancing these systems.

Ties with Russia and growing tensions on the peninsula

Questions persist about how North Korea sources the technology and materials needed to build a nuclear-powered submarine. Some analysts point to Pyongyang’s growing alignment with Russia, including its support for President Vladimir Putin’s war in Ukraine, as a possible avenue for technical assistance.

Although there has been speculation that North Korea could obtain a reactor from Russia, perhaps from a retired submarine, Moon said it was more likely that the country had designed its own reactor, although outside help may have been involved.

Separately, KCNA reported that Kim on Wednesday oversaw a test of a new long-range anti-aircraft missile fired toward the Eastern Sea. South Korea’s Defense Ministry had no immediate comment.

These developments come as tensions on the Korean Peninsula continue to escalate. North Korea has rejected renewed calls from Washington and Seoul to resume negotiations aimed at scaling back its nuclear and ballistic missile programs, which stalled after a failed summit with Trump in 2019.