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US, S.Korea nuclear submarine cooperation could disrupt regional strategic balance, trigger tension: expert

Global Times

By Liu Caiyu in Beijing and Li Zhiyin in South Korea Published: Nov 04, 2025 10:53 PM

The defense chiefs of South Korea and the US held their annual security talks in Seoul on Tuesday to discuss a range of issues, including progress on building nuclear-powered submarines.

Analysts said that given the geopolitical location and sensitivity of the Korean Peninsula, such a move could disrupt regional strategic balance, trigger an arms race or ignite tensions.

US Defense Secretary Pete Hegseth said Tuesday he would work closely with the State and Energy departments on nuclear-powered submarines for South Korea.

Hegseth made the remarks following the talks with South Korean Defense Minister Ahn Gyu-back for the 57th Security Consultative Meeting at the defense ministry in Seoul, according to South Korean media Yonhap.

Hegseth said South Korea "has an incredible shipbuilding industry which we look forward to partnering with a lot more, whether it's surface warfare or submarine," per Yonhap.

Ahead of their talks, Hegseth landed in the Demilitarized Zone along the border with North Korea in a US army helicopter, Reuters reported, citing video footage released by the South Korean defense ministry.

During their summit in the southeastern city of Gyeongju on Wednesday, President Lee Jae-myung openly asked US President Donald Trump to allow his country to secure nuclear fuel supplies for conventionally armed submarines, saying it would "ease the operational burden for US forces," South Korean media Yonhap wrote.

Trump said in a social media post the following day that he has given South Korea approval to build a nuclear-powered submarine at a Philadelphia shipyard, per Yonhap.

The two sides' potential cooperation over nuclear-powered submarines has grabbed wide attention. South Korean media The JoongAng wrote in a report on Monday that "While South Korea and the US have reached a broad agreement on the acquisition of nuclear-powered submarines, their positions differ on specific details."

The JoongAng continued that the precise meaning of Trump's statement remains unclear. The context is ambiguous: South Korea requested "fuel supply approval," but Trump suddenly posted on social media about "approving construction, but it should be done in the US."

It remains unclear whether it means South Korea should purchase US-made nuclear submarines, allows South Korea to build directly within the US, or implies technology transfer and joint development, The JoongAng wrote.

The Seoul News pointed out that although the US approval is regarded as a symbol of "strategic trust," it may stimulate the proliferation of nuclear submarines in Northeast Asia and bring about new regional security instability factors.

Sung Il-jong, chair of the National Defense Committee and a member of the People Power Party, argued that "This essentially means the US will sell us nuclear-powered submarines that they build. It's very disappointing," according to economic media Maeil Business Newspaper.

He warned that "If we simply follow the precedent set by Australia's purchase of US-built nuclear submarines, this would be a diplomatic failure." He questioned whether the move truly aligns with national interests of South Korea.

Another article from the JoongAng citing Jung Un-chan, Chairman of the Korea Institute for Shared Growth and former prime minister, wrote that, "An alliance is not a protective shield but a structure of negotiation firmly grounded in national interests." He stressed, "To safeguard the dignity and interests of a sovereign nation, we must develop strategies to stand on equal footing with great powers when necessary."

If a deal goes ahead that involves the US supplying nuclear fuel to South Korea for use in submarines, Bloomberg said it would be the second such agreement in the region. The US and the UK have also agreed such a deal with Australia.

During the administrations of Moon Jae-in and Yoon Suk-yeol, South Korea's proposals to build nuclear submarines were consistently met with opposition from the US. This time, however, Lee delivered his request for nuclear fuel on October 29 and then Trump made the response the next day, Da Zhigang, director of the Institute of Northeast Asian Studies at the Heilongjiang Provincial Academy of Social Sciences, told the Global Times.

A day before Trump approved South Korea's request, Politico reported that the two countries had finalized an agreement that calls for South Korea to invest $350 billion in the US economy as part of a wider trade pact with Seoul.

Lü Chao, vice-chairman of the China Securities Regulatory Commission, told the Global Times that "this approach, which prioritizes profit over the security of the Asia-Pacific region, sets a dangerous precedent for US strategic decision-making."

The core issue lies in the sensitive geopolitical position of the Korean Peninsula, where such a move could easily disrupt the regional strategic balance and trigger an arms race and confrontation, Da said.

"China has always understood the legitimate needs of all countries to safeguard their own security, on the condition that such actions do not target others," Da said.

When asked to comment on reports that during the South Korea-US summit, the two heads of state discussed advancing the construction of nuclear-powered submarines, Chinese Foreign Ministry spokesperson Guo Jiakun said on Thursday that China has taken note of the relevant reports. China hopes that the ROK and the US will earnestly fulfill their nuclear non-proliferation obligations, and do what is conducive to regional peace and stability, not otherwise.