North Korea Refurbishing its First Nuclear Ballistic Missile Submarine Built for Strikes on U.S. Forces

Commercial satellite imagery has revealed North Korea’s first ballistic missile submarine, the unique sole vessel of the Gorae class ship, has been placed in drydock at the Sinpho South Shipyard, fuelling speculation that it may be benefitting from upgrades and refurbishment work. The submarine represents an earlier stage in the country’s efforts to develop a submarine-launched ballistic missile capability, and was first used to test ballistic missiles in 2016. The submarine is considerably smaller and less capable than more recent North Korean ballistic missile submarine concepts, with the country’s submarine industry having matured considerably over the past decade allowing it to make progress on constructing its first nuclear powered submarine.

Imagery from late April showed netting that had previously obscured the drydock removed, allowing the 8.24 Yongung to be identified inside the facility. The vessel was subsequently observed back in the secure boat basin alongside a support vessel. The movements indicate that the submarine spent at least some period in the shipyard’s drydock, although the precise nature and extent of the work being undertaken remain unclear. While it was previously thought that the vessel was designed primarily as an experimental testbed rather than as a mature operational strategic submarine, ongoing investment in refurbishing the vessel may indicate that it is intended for operational service. 

North Korean state media in December 2025 published the first images of the country’s long anticipated first nuclear powered submarine, revealing that the ship is currently under construction and displaces 8,700 tons. This follows reports from South Korean military sources in October 2024 that the North had begun construction of the first nuclear submarine, an reports for several years from North Korean government sources that the development of such a ship is planned. Testing work done on the Gorae class, including the development of multiple generations of submarine-launched ballistic missiles, has been key to facilitating this. It remains uncertain whether the older submarine will continue to be used for training purposes, or whether upgrades may allow it to assume a more active role in service. 

The ability launch strikes against the U.S. mainland, and against U.S. military facilities across the Pacific, has long been highly prized by Pyongyang, as the United States has on multiple occasions come close to launching attacks on the country including major nuclear strikes. President Barak Obama favoured an attack in 2016, and was reportedly deterred only by to warnings from the Pentagon, while his successor Donald Trump in 2017 drew up plans for mass nuclear attacks which were expected to kill millions of Koreans. The unprovoked strikes were on both occasions deterred largely by North Korean retaliatory capabilities. The development of a robust submarine nuclear deterrent will complement advances made to the country’s conventional forces and its land-based nuclear deterrent.