North Korea on Thursday signaled apparent progress in the construction of a nuclear-powered submarine, with state media releasing images that appear to show a largely completed hull, as leader Kim Jong Un criticized South Korea’s efforts to pursue similar technology.
North Korea’s state-run Korean Central News Agency said Kim recently visited a shipyard to inspect work on what the country describes as an 8,700-ton-class nuclear-propelled submarine. Kim has portrayed the vessel as a key element in modernizing and nuclear-arming North Korea’s navy, with plans to equip it with nuclear-capable missiles. North Korean officials have referred to the submarine as both a “strategic guided missile submarine” and a “strategic nuclear attack submarine.”
During the visit, Kim denounced South Korea’s push to acquire its own nuclear-powered submarine — an effort backed by U.S. President Donald Trump — calling it an “offensive act” that he said threatens North Korea’s security and maritime sovereignty. He argued that the South’s plans reinforce the need for Pyongyang to further strengthen and nuclear-arm its naval forces, describing the completion of the submarine as an “epoch-making” advancement in the country’s nuclear deterrent.
KCNA did not specify when the inspection took place but released photos showing Kim touring an assembly hall alongside senior officials and his daughter. The images depict a massive, burgundy-colored vessel coated in what appears to be anti-corrosion paint. It marked the first time North Korean media have shown nearly the entire submarine since March, when earlier images focused mainly on lower sections of the hull.
While it remains unclear how close the vessel is to completion, analysts said the visible progress suggests significant internal work may already be finished. Because submarines are typically built from the inside out, the appearance of a largely completed hull indicates that key components — including the engine and potentially the nuclear reactor — could already be installed, said Moon Keun-sik, a professor at Hanyang University and a former South Korean navy submarine officer.
“Showing the entire vessel now seems to indicate that most of the equipment has already been installed,” Moon said, adding that the submarine could potentially undergo sea trials within months.
Kim first outlined plans for a nuclear-powered submarine during a major ruling-party conference in 2021, when he unveiled a list of advanced weapons systems intended to counter what he described as growing U.S.-led military threats. The list also included solid-fueled intercontinental ballistic missiles, hypersonic weapons, reconnaissance satellites, and multi-warhead missiles.
North Korea has since conducted a series of tests related to those systems and recently unveiled a new naval destroyer, which Kim praised as a step toward expanding the operational range and preemptive strike capabilities of the country’s nuclear forces.
Military analysts warn that a nuclear-powered submarine capable of extended underwater operations and missile launches would significantly complicate regional security, as underwater launches are far more difficult to detect. However, questions remain over whether North Korea — an impoverished country under heavy international sanctions — possesses the resources and technical expertise needed to field such a platform.
Some experts believe Pyongyang’s deepening alignment with Russia, including its reported deployment of troops and military equipment in support of Russian President Vladimir Putin’s war in Ukraine, may have helped North Korea obtain key technologies. While some analysts speculate that North Korea could have sought a nuclear reactor from Russia, possibly from a retired submarine, Moon said it is more likely Pyongyang developed its own reactor design with limited outside assistance.
South Korean President Lee Jae Myung raised the issue of nuclear-powered submarines during a summit with Trump in November, calling for U.S. backing while pledging increased defense spending to ease the burden on Washington. Trump later said the United States was open to sharing closely held technology, though questions remain about where such a submarine would be built and how South Korea would secure nuclear fuel and reactor technology.
In a separate report, KCNA said Kim on Wednesday oversaw tests of newly developed surface-to-air missiles fired into the sea. South Korea’s Joint Chiefs of Staff later confirmed detecting multiple missile launches from North Korea’s east coast, saying U.S. and South Korean intelligence agencies were analyzing the details.
Tensions on the Korean Peninsula have intensified in recent years as Kim accelerates his nuclear weapons program and strengthens ties with Moscow. North Korea has repeatedly rejected calls from Washington and Seoul to resume negotiations aimed at rolling back its nuclear and missile activities, which collapsed in 2019 after a failed summit between Kim and Trump during Trump’s first term.
