How US nod to South Korea’s joining nuclear sub club could reshape strategic landscape

The United States has given South Korea the green light to build nuclear-powered submarines – a landmark decision that could significantly boost Seoul’s naval capabilities and place it among a select group of nations with such assets. Analysts say the move could reshape Northeast Asia’s strategic landscape in ways that not only strengthen deterrence but also reduce the risk of open conflict, as Washington recalibrates its alliance priorities under President Donald Trump. Trump announced the decision last week, revealing that it followed successful trade negotiations with South Korean President Lee Jae-myung. He said the new vessel would replace South Korea’s “old fashioned and far less nimble diesel-powered submarines” and be constructed at a shipyard in Philadelphia run by South Korean conglomerate Hanwha. The move is set to admit Seoul to an exclusive club of nations that possess such vessels: the US, China, Russia, the UK, France and India. On Tuesday, US Secretary of Defence Pete Hegseth reiterated that Washington fully backed Seoul’s plan to develop nuclear-powered submarines. “President Trump has approved this historic step, and I want to reaffirm that decision,” Hegseth said in Seoul during a joint press conference with South Korean Defence Minister Ahn Gyu-back. Adding that the US defence department would actively and fully support the decision, Hegseth said the nuclear submarine programme would strengthen the bilateral alliance as well as Seoul’s defence. “South Korea has world-class shipbuilding capabilities, and the US looks forward to expanding cooperation not only in submarines but also in surface warfare,” he said. Yang Uk, research fellow and director at The Asan Institute for Policy Studies’ Centre for Foreign Policy and National Security, said the possession of nuclear submarines would have significant implications for international politics and security in Northeast Asia. “Nuclear submarines are an inherently geopolitical weapons system,” Yang said. Such vessels combine stealth, endurance, global reach and strategic deterrence. They can remain submerged for months, making them highly resistant to a first strike and thus a stabilising element in nuclear strategy. By reducing the temptation for pre-emptive attacks, they help shape the strategic decision-making of major powers. Deepening ties While there were concerns that Seoul’s acquisition of nuclear submarines could worsen relations with China, Yang said this would not be the case. “The risk that a deterioration in bilateral ties could lead to a naval clash – causing severe damage to both sides – could instead serve as a powerful incentive for maintaining stable and positive relations between South Korea and China,” Yang said. Jennifer Parker, expert associate at the Australian National University’s National Security College, said many questions remained about how the project would work. “We still don’t know what the submarine design will be or how the programme will be supported,” Parker said, adding that Seoul does not need nuclear-powered vessels in the same way Australia does. “South Korea has a strong and modern navy, but nuclear-powered submarines are a major step up and will require time, infrastructure and deep specialist capability,” she said. According to Parker, the initiative’s success will add to the proliferation of nuclear-powered boats in the region and also “strengthen the balance against China’s expanding nuclear submarine fleet”. Huong Le Thu, deputy director of the Asia Program at the International Crisis Group, said providing a nuclear-powered submarine for South Korea would equip Seoul with a more potent capability to deter North Korea, which is supported by Russia. It would also “deepen defence ties between [Washington] and Seoul amidst some worries about America’s commitment to allies in general”, she said. Though it might take “a couple of decades” to have a fully operational nuclear-powered submarine fleet, the move was likely to expand South Korea’s maritime outlook beyond the Korean peninsula, Le Thu said. She added that Aukus may be uppermost on Trump’s mind, given the recent successful meeting between him and Australian Prime Minister Anthony Albanese. “So perhaps that inspired [Trump] to expand to others,” Le Thu said. Aukus refers to the trilateral defence security pact between Australia, the UK and the US aimed at providing nuclear submarines to help Canberra deter Beijing’s growing influence in the region. During their White House meeting last month, Trump and Albanese reaffirmed the Aukus agreement, with Trump declaring the deal would proceed “full steam ahead”, ending months of speculation about the future of the pact under his administration. Yang added that South Korea had initially asked the US to provide nuclear fuel for use in its submarines, but Washington responded by suggesting that Seoul build its nuclear submarines at the Hanwha Shipyard in Philadelphia. “This implies that the submarines will be constructed based on Korean-developed technology and Korean design” and not its American counterparts, he noted. However, certain aspects such as reactor noise reduction could still make use of US technical support during the construction process, Yang added. Offering to share US nuclear submarine technology with South Korea is said to have made Aukus – the trilateral defence agreement between Australia, the UK and the US – less exclusive. Washington shares its naval nuclear propulsion technology only within the Anglosphere: the UK, a long-standing partner, and Australia. Yang said what made Aukus distinctive was that the two anglophone powers, the US and the UK, had chosen to support Australia’s ambition to play a greater role in the Indo-Pacific region. However, under Trump’s second administration, scepticism was emerging over sustained US support for Australia, Yang said, noting that Japan was likely to seek access to US nuclear submarine technology similar to what Australia is receiving. “Tokyo will be closely watching how South Korea proceeds with building its submarines within the US,” Yang added.

How US nod to South Korea’s joining nuclear sub club could reshape strategic landscape

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}The move would not only strengthen deterrence but also reduce the risk of open conflict in Northeast Asia, analysts say

The move would not only strengthen deterrence but also reduce the risk of open conflict in Northeast Asia, analysts say