The government of South Korea recently announced that it has reached a historic agreement with the United States to begin the development of new nuclear-powered attack submarines, a step that would mark a before-and-after in the maritime projection capabilities of the Republic of Korea Navy. According to reports, Washington would have given its formal approval to the project, also committing to cooperate in the supply of the nuclear fuel required for its implementation in the coming years.
The confirmation of the agreement represents a significant advance compared with what was reported at the end of October, when Washington had expressed its initial willingness to support South Korea’s plans to develop a new generation of nuclear-powered submarines. At that time, the negotiations were still in a preliminary phase, focused on evaluating technical feasibility, regulatory requirements, and the impact on commitments established in the civil nuclear treaty between both countries. The formalization of the understanding thus marks the transition from a consultative stage to concrete cooperation, aligned with Seoul’s strategic objectives amid an increasingly complex regional environment.
The understanding between both governments is framed within a broader bilateral agreement signed after the leaders’ meeting in early October, which also included commitments on trade and the reduction of reciprocal tariffs, from 25% to 15%. According to the official statement from the U.S. government, “The United States approves the Republic of Korea to build nuclear-powered attack submarines and will work closely together on the project’s requirements, including pathways for the supply of fuel.”
In parallel, U.S. President Donald Trump posted on his Truth Social platform that the new submarines would be built at a shipyard located in Philadelphia, which would be managed by the South Korean conglomerate Hanwha Ocean, one of the main companies in South Korea’s naval industry and currently responsible for constructing the new KSS-III Batch II ballistic-missile submarines.
Currently, the Republic of Korea Navy (ROKN) operates a fleet of around 20 diesel-electric submarines of domestic manufacture, built over the past decades as a result of cooperation agreements with other countries. Unlike these units, the future nuclear submarines would allow South Korea to maintain prolonged and discreet operations underwater, increasing its surveillance capacity and strategic deterrence capability. Although the country has extensive experience in the field of civil nuclear energy, its ability to enrich uranium remains limited by agreements signed with Washington in the 1970s, when Seoul abandoned its nuclear weapons program under U.S. pressure.
The decision to move forward with this new program is directly linked to the deterioration of the security environment in Northeast Asia, where Seoul seeks to strengthen its ability to respond to the growing threats from North Korea, which has claimed to be developing its own nuclear-powered submarine, as well as to the intensification of Chinese naval activity near the peninsula. Both circumstances have pushed the South Korean government to accelerate the modernization of its Armed Forces and to deepen technological and strategic cooperation with the United States.
*Photographs used for illustrative purposes: nuclear submarine USS Vermont (SSN 792) arriving at Busan Naval Base, South Korea, in 2024 – Credits: Mass Communications Specialist Seaman Apprentice Robert A. Moses.
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