North Korea on March 8 released images of leader Kim Jong-un inspecting the construction of what it calls a “nuclear-powered strategic guided missile submarine,” marking its first public acknowledgment of the project.
The submarine, believed to be a nuclear-powered ballistic missile submarine (SSBN), is one of five key military projects Kim pledged to develop during a ruling party congress in January 2021. While Pyongyang has previously alluded to nuclear submarines, this marks its first visual confirmation of one under construction.
Speculation suggests North Korea may have obtained nuclear submarine technology from Russia in exchange for military aid in Ukraine.
According to the state-run Korean Central News Agency (KCNA), Kim inspected the construction site and emphasized the vessel’s role in strengthening North Korea’s nuclear deterrence. The exact location and timing of his visit were not disclosed.
SSBNs, powered by nuclear reactors, can remain submerged for extended periods and launch ballistic missiles, potentially altering the strategic military balance.
In September 2023, North Korea unveiled the Hero Kim Kun Ok, a submarine it described as a “nuclear attack submarine,” though analysts determined it was a conventionally powered vessel capable of launching submarine-launched ballistic missiles (SLBMs).
Photos released by state media show Kim walking alongside the partially constructed submarine while receiving briefings from officials.
Moon Keun-sik, a professor at Hanyang University and a former South Korean navy submarine captain, said the images suggest the visit took place at the Sinpo Shipyard in South Hamgyong Province. He estimated the submarine’s displacement at between 5,000 and 8,000 tons—more than twice the size of the Hero Kim Kun Ok, which is around 3,000 tons.
A South Korean military official said the new submarine appears significantly larger than the Hero Kim Kun Ok but cautioned that even if North Korea has developed nuclear propulsion, it would likely take another two to three years before the vessel is operational. Additional years would be needed to master nuclear-powered submarine operations.
However, if Pyongyang has received assistance from Moscow in developing compact nuclear reactors capable of withstanding deep-sea pressure, the development timeline could be shortened. South Korean military authorities are closely monitoring potential military-technology transfers between North Korea and Russia.
Alongside the submarine, North Korea also released images of what appeared to be a 4,000-5,000-ton warship under construction, possibly a destroyer or frigate. Compared to images from late 2024, the vessel’s superstructure appeared more complete, with radar equipment installed.
With this latest disclosure, analysts say Kim is steadily advancing his five key military projects, which include weapons systems capable of striking targets across the Korean Peninsula and even the U.S. mainland. In recent years, North Korea has claimed success in testing hypersonic missiles, solid-fuel intercontinental ballistic missiles (ICBMs), and multiple independently targetable reentry vehicles (MIRVs). It also launched a reconnaissance satellite in late 2023, which Pyongyang claimed was successful, despite its low resolution compared to commercial satellite imagery.
North Korea’s decision to reveal SSBN construction could also be a strategic move to attract attention from U.S. President Donald Trump, who has suggested openness to renewed dialogue with Pyongyang.
Yang Uk, a research fellow at the Asan Institute for Policy Studies in Seoul, said North Korea is not only developing tactical nuclear ballistic missiles capable of striking South Korea but is also pushing ahead with SSBN construction. “The South Korean military must enhance its weapons systems and upgrade U.S.-South Korea joint defense readiness to counter North Korea’s nuclear submarine threat,” he said.
