South Korea’s ambition for nuclear-powered submarines received a boost when President Donald Trump announced on 29 October 2025 that the US government had given a green light for Seoul to build such boats on American soil.

Gordon Arthur story, additional reporting by Eunhyuk Cha

In February 2026, Korea’s Ministry of National Defense announced that it is pushing to enact a special law to support the acquisition of nuclear-powered submarines in a stable and systematic manner. The Ministry views the nuclear submarine program as a national strategic project that will require large-scale, long-term budgetary commitments and sustained national effort. Additionally, since the existing legislation are designed for civilian nuclear energy, ministry finds need for a comprehensive regulatory framework established for military use of nuclear energy.

However, South Korea has been eyeing the prospect of such submarines for some time already. One evidence was when Hanwha Ocean displayed a new submarine concept at MADEX 2025, a naval exhibition held in Busan from 28-30 May last year.

A scale model of the radical Future Submarine was showcased, with a graphic displayed alongside listing “customer requirement” for the propulsion choices available. Obviously, this includes nuclear power as an option alongside conventional diesel-electrics, as all Republic of Korea Navy (ROKN) submarines are at present.

There are some in South Korea who see nuclear-powered submarines as inevitable, though industry sources suggested to Naval News that South Korea would never be the first to introduce nuclear power to submarines. This is because it would be considered too provocative for its belligerent neighbor to the north.

However, with North Korea having announced in March 2023 that it had launched a nuclear-powered missile-armed submarine, Seoul likely feels justified in reciprocating. Pyongyang then unveiled its nuclear-powered ballistic-missile submarine in December 2025, with state imagery showing it at an advanced stage of construction. It likely displaces more than 8,000 tonnes, and can carry ten ballistic missiles.

A North Korea in possession of such submarines forces Seoul into seriously considering responding with nuclear-powered submarines of its own.

The purpose of the model displayed at MADEX 2025 was to illustrate the directions that Hanwha Ocean plans going with submarines in the future. The craft is replete with technological leaps, including a rim-driven propulsor that reduces cavitation and thus noise. A traditional propeller has a central hub, but the rimless-driven design dispenses with this. However, the drawback is that such systems are expensive to manufacture.

The Future Submarine also has an X-form rudder, as well as retractable bow planes that aid submerged diving performance. Stealth and quietness are themes that run throughout the design concept, which would feature a dual-layer acoustic coating.

Other features of the proposed design are a diver lockout where special operations frogmen and autonomous underwater vessels can disembark or return. Manned-unmanned teaming opportunities would form a central tenet of the design.

The hull form, which includes an expandable flank array sonar, is sleek with a very low sail. The latter features an electro-optical mast that offers a 360º view. This means the operator in the integrated combat command centre does not need to rotate the periscope, for the surroundings in every direction are immediately captured.

There is a sizeable vertical launch section for missiles, whilst a new technology would be used to launch torpedoes and other objects from the bow tubes more quietly. There would also be an artificial intelligence-based combat management system to reduce crewing requirements.

A Hanwha Ocean spokesman told Naval News that the design is very much a concept, but that if the ROKN wanted such a vessel, it could be achieved if given enough time.

Nonetheless, the Future Submarine should be considered simply as a showcase of new technologies that might eventually appear in future South Korean submarine designs. Of course, given Trump’s tacit approval for the transfer of nuclear technologies, a nuclear-powered design becomes a stronger possibility.

Hanwha Ocean acquired the Philadelphia Shipyards in late 2024, but things are not as straightforward as Trump’s tweet suggests. That site is not equipped to handle the construction of nuclear-powered submarines, and to date there is no concrete agreement between Seoul and Washington DC.

Furthermore, former ROKN Chief of Naval Operations Kang Dong-gil stated last year, “The start date for the nuclear-powered submarine programme has not yet been decided, but once it begins, it will take more than ten years.”

South Korea would also have to decide whether to add a nuclear reactor to the KSS-III submarine design currently under construction for the ROKN, or to pursue a clean-sheet design such as Hanwha Ocean’s Future Submarine.

Check out Naval News’ video coverage of Hanwha Ocean’s future submarine concept at MADEX 2025:

The post South Korea is already preparing for nuclear-powered submarines appeared first on Naval News.

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• Naval News: South Korea is already preparing for nuclear-powered submarines