South Korean President Lee Jae Myung has called on US President Donald Trump to revise a decades-old nuclear energy agreement, requesting approval for nuclear fuel supply to build conventionally armed submarines.

The request came during a bilateral meeting in Gyeongju on Wednesday, as Seoul pushes to expand its maritime capabilities amid mounting tensions with both the Democratic People's Republic of Korea and China.

“If we could secure approval for nuclear fuel supply, we would be able, using our own technology, to build several conventionally armed submarines,” Lee told Trump during their public exchange. “They could patrol and defend both the East and West Seas of the Korean Peninsula, which in turn would significantly reduce the operational burden on US forces.”

Lee clarified that the request was not related to developing nuclear weapons, but rather to replacing aging diesel-powered vessels currently unable to effectively monitor regional threats.

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South Korea seeks fuel for submarine use, not weapons

South Korea’s request would require amendments to the 123 Agreement, a bilateral deal signed in the 1970s governing the peaceful use of nuclear energy. The agreement prohibits South Korea from reprocessing spent nuclear fuel without Washington’s explicit consent, a restriction rooted in US-led non-proliferation efforts and aimed at preventing nuclear weapons development on the Korean Peninsula.

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While Japan already holds the right to reprocess nuclear fuel, South Korea has remained bound by stricter terms. The agreement was last revised in 2015 and remains in effect until 2035.

Seoul argues that its request is based on environmental and operational needs, not military ambitions.

Trump pledges support without direct commitment

Trump did not directly respond to Lee’s proposal during their joint remarks but expressed willingness to deepen defense ties.

“Our defense is very important from the standpoint of helping other countries,” Trump said. “But we’re going to take care of, we’re going to work with you.”

The US has previously entered into similar agreements in the region. Under the AUKUS pact, Washington and London are transferring submarine-specific material and technology to Australia for its planned fleet of nuclear-powered submarines.

Diplomatic courting as Seoul faces pressure from China and DPRK

The South Korean government has worked to strengthen its relationship with Trump, awarding him the Grand Order of Mugunghwa, the country's highest state honor. President Lee also gifted Trump a replica of a gold crown on display at the Gyeongju National Museum.

Following his meeting with Trump, Lee is scheduled to meet with Chinese President Xi Jinping, their first summit since Lee took office in June.

In recent remarks, Lee described South Korea as a nation caught between “two grinding stones,” referencing escalating rivalry between the US and China. Both nations remain Seoul’s largest trading partners.

China’s economic influence on South Korea was underscored earlier this month when Beijing imposed curbs on five US-based units of Hanwha Ocean Co. after the South Korean shipbuilder announced investment plans in the US maritime sector.