On November 4, 2025, at a South Korean State Council meeting, President Lee Jae Myung was presented a plan to build South Korea’s first nuclear-powered submarine. The United States has approved this long-term project, and while Seoul has portrayed it as a victory for Korean diplomacy, the author believes it is a trap.
What happened, and what did Seoul get?
Seoul’s pursuit of a nuclear-powered submarine began several decades ago. Previous administrations considered the idea, but all attempts stalled due to opposition from the United States.
On October 29, 2025, during a summit in Gyeongju, South Korean President Lee Jae Myung publicly asked US President Donald Trump to allow South Korea to purchase nuclear submarine fuel and promised to increase defense spending to strengthen the country’s military capabilities.
As stated by Wi Sung-lac, National Security Advisor to the South Korean President, “President Trump agrees that the Republic of Korea needs nuclear-powered submarines and expressed his intention to hold subsequent consultations.” Trump confirmed on his Truth Social account that an agreement was reached to provide Seoul with fuel for nuclear submarines. To this end, the South Korean side gained the rights to reprocess nuclear fuel and enrich uranium. Trump added that the nuclear-powered submarines for the South Korean navy would be built at shipyards in Philadelphia, which would be a major success for the American shipbuilding industry.
Lee Jae Myung noted that diesel-electric submarines have limited underwater endurance, which restricts the South Korean military’s ability to track North Korean or Chinese submarines.
In response, Lee promised that the Republic of Korea will increase defense spending and develop its defense industry to significantly enhance its self-defense capabilities.
Experts note that Washington was willing to share – for the first time – technologies that had not even been transferred to Britain and Australia under AUKUS. Previously, South Korea was only permitted to enrich uranium below 20% with US consent, and the reprocessing of nuclear fuel was prohibited.
Meanwhile, Foreign Minister Cho Hyun stated that South Korea does not intend to develop its own nuclear weapons: “We have extended deterrence from the US, and we see no need to develop our own nuclear weapons.” In his view, nuclear-powered submarines “are in no way related to nuclear capabilities or the potential to create nuclear weapons.”
Technical difficulties
According to South Korean Chief of Naval Operations Admiral Kang Dong-gil it will take South Korea approximately 10 years to acquire its first nuclear-powered submarine. Deputy Minister of Defense for Resource Management Won Jong-dae also believes that the submarine could be launched in the mid-to-late 2030s if South Korea secures fuel for itself through consultations with the US and begins construction in the late 2020s.
Meanwhile, Minister of National Defense Ahn Gyu-back stated that, in his opinion, the country should acquire four or more nuclear-powered submarines, which would be of “immense” military significance in countering North Korea’s nuclear capabilities.
However, some disagreements are already taking shape regarding where the submarines will be built. On November 4, US Secretary of War Pete Hegseth said that Washington would make an effort across departments to help South Korea fulfill the US president’s promise to build the nuclear-powered submarines at an American shipyard.
Ahn Gyu-back revealed that no specific details, including whether the submarines would be built at a US shipyard, have been discussed with the United States. It is claimed that the shipyard in Philadelphia currently lacks the necessary technology, workforce, and infrastructure, and that creating the necessary environment for building nuclear submarines would take five to ten years. Therefore, building them domestically is preferable.
Wi Sung-lac also stated that Seoul will strive to build the nuclear-powered submarine domestically.
Furthermore, it remains likely that both sides have yet to reach a full mutual understanding on key security issues, particularly on how to permit Seoul to produce its own fuel for nuclear-powered submarines. This would require either a revision of the nuclear energy pact or the signing of a separate agreement.
The Chinese Huanqiu noted that the South Korea-US program for building nuclear-powered submarines faces four main obstacles. The first is related to US non-proliferation policy. The US government or Congress might oppose Seoul’s acquisition of nuclear-powered submarines due to concerns about potential South Korean nuclear weapons. The second is related to the protection of US military technologies, as they have never transferred nuclear submarine technology to any other country. The third is related to operational limitations. The fourth is the uncertainty of the future alliance between South Korea and the United States.
Conservative media outlets are critical of the project. From their perspective, Trump’s approval only meant that Korea could purchase and operate submarines built by American engineers at a shipyard in Philadelphia, without the transfer of nuclear technology or fuel. Such an agreement holds little strategic value for a country that does not possess its own nuclear weapons. The true significance of nuclear-powered submarines lies in their ability to provide a second-strike capability when combined with nuclear weapons. A nuclear-powered submarine without nuclear weapons is not a shield, but a costly illusion.
Potential consequences for Seoul
Although the construction of nuclear-powered submarines does not formally violate the NPT, the Chinese foreign ministry immediately called on South Korea and the United States to adhere to their non-proliferation commitments: “China hopes that both South Korea and the US will fulfill their non-proliferation obligations and act in a way conducive to regional peace and stability, rather than the opposite,” stated Chinese foreign ministry spokesperson Guo Jiakun.
As noted by the Chinese Guancha: “Under the guise of institutional innovation, the UK and the US are actually loosening the rules, turning the IAEA into a rubber-stamp machine and undermining the authority of the non-proliferation mechanism. Pandora’s box has been opened, and the international community will have to face a new reality of uncontrolled proliferation of nuclear technologies”.
Expert opinions are divided. Doo Jin-ho, head of the Eurasian Research Center at the Korea Research Institute for National Strategy, called the acquisition of nuclear-powered submarines a major diplomatic victory for President Lee. Although previous US administrations rejected the idea due to concerns related to the NPT, Trump’s more business-oriented approach helped make the deal possible.
Park Won-gon, professor of North Korean studies at Ewha Womans University, believes that it was a mistake for the president to publicly mention China. This should have been discussed behind closed doors. Beijing may perceive this as a serious provocation against the backdrop of Seoul’s growing military and shipbuilding ties with Washington.
Victor Cha, president of the Geopolitics and Foreign Policy Department and Korea chair at the Center for Strategic and International Studies (CSIS), also suggested that in response to South Korea’s US-backed pursuit of nuclear-powered submarines, China might take retaliatory measures, including economic coercion.
Furthermore, it is highly likely that South Korea’s acquisition of its own nuclear-powered submarine will serve as an additional catalyst for an arms race in the region. Tokyo might also consider acquiring its own nuclear-powered submarines, while Beijing and Pyongyang could use the situation to justify further countermeasures, including nuclear escalation.
To conclude
As noted by Russian journalist and scholar Oleg Kiryanov: “Overall, this aligns with Trump’s policy to make allies pay more for their own defense and military and to use this to contain the US’s main strategic rival – China”. The submarine will be built in 10 years, but problems for Seoul are starting already.
The reason why North Korea wants a nuclear-powered submarine is clear, given its confrontation with the US. But who is South Korea’s adversary significant enough for it to require a nuclear-powered submarine? This is similar to the South’s missile development programs, from which all restrictions have been lifted, or Moon Jae-in’s discussions about the need for an aircraft carrier. This seems excessive even for a war to reclaim the “Northern Territories,” and therefore Moscow and Beijing should consider countermeasures.
Konstantin Asmolov, PhD in History, leading research fellow at the Centre for Korean Studies of the Institute of China and Modern Asia at the Russian Academy of Sciences
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