South Korea Gains US Support for Nuclear Submarine Programme

Published: 17 November 2025 Monday. The English Chronicle Desk. The English Chronicle Online

South Korea and the United States have taken a significant step in their security partnership, with Seoul finalising an agreement to build nuclear-powered submarines with American support. The announcement, made by the South Korean government, signals a major advancement in the nation’s naval capabilities and comes amid rising tensions on the Korean Peninsula, where North Korea’s nuclear ambitions and an increasingly assertive China pose ongoing strategic challenges.

According to a White House fact sheet released on Thursday, the United States has granted approval for South Korea to develop “attack submarines,” and has pledged to assist in sourcing nuclear fuel for the vessels. This development follows a broader context of enhanced bilateral cooperation, including a recent trade agreement between the two nations that lowered reciprocal tariffs from 25% to 15%, a move negotiated by South Korean President Lee Jae Myung.

The submarine programme represents a substantial shift in Seoul’s military strategy. Currently, South Korea operates around 20 submarines, all diesel-powered. While effective for coastal patrols, these vessels must surface frequently and have limited operational range. Nuclear-powered submarines, by contrast, offer longer endurance, greater speed, and enhanced stealth capabilities, enabling them to project power further from home waters and maintain a continuous deterrent posture. The strategic advantage of such vessels is particularly pronounced given North Korea’s recent announcements of its own nuclear submarine programme, which President Lee highlighted as a key rationale for the initiative during his discussions with US leaders at the APEC summit last month.

US President Donald Trump, who confirmed the arrangement via his social media platform Truth Social, said the vessels would be constructed at a Philadelphia shipyard operated by the South Korean conglomerate Hanwha. Trump described the move as a replacement for South Korea’s “old-fashioned” diesel submarines, enabling the country to deploy a more nimble and capable naval force.

“South Korea now has the opportunity to operate nuclear-powered submarines rather than the older diesel-powered vessels that required frequent surfacing,” Trump said. “This is a substantial upgrade in terms of speed, endurance, and stealth.”

The deal places South Korea among a select group of nations with nuclear-powered strategic submarines, joining the United States, China, Russia, the United Kingdom, France, and India. While South Korea has extensive experience with civilian nuclear energy, its nuclear weapons programme from the 1970s was abandoned under US pressure. Consequently, Seoul relies entirely on imported nuclear fuel for its new military vessels, a dependency that the US has committed to supporting under the current agreement.

South Korea’s Defence Minister, Ahn Gyu-back, described the programme as a “proud achievement” for the country. Speaking on national television last week, he said that the submarines would significantly enhance the nation’s ability to counter North Korean threats. “The stealth and reach of nuclear submarines will ensure that North Korea remains vigilant and aware of our capabilities,” he remarked, underscoring the strategic deterrent effect the vessels are intended to provide.

The initiative comes at a time of heightened geopolitical tensions in the region. North Korea has accelerated its nuclear weapons development, including the testing of long-range missiles capable of reaching the continental United States. Meanwhile, China has continued to expand its military presence in the East and South China Seas, further complicating security dynamics for Seoul. The addition of nuclear-powered submarines to South Korea’s arsenal will provide the country with a more flexible and resilient deterrent, allowing it to respond to multiple potential threats simultaneously.

Experts note that the agreement also has broader implications for the US-South Korea alliance. The submarine programme, along with the recent trade deal, reflects a deepening of bilateral ties and a shared commitment to countering regional security threats. The trade deal itself, which involves significant South Korean investment in the US—including $200 billion in cash investment and $150 billion in shipbuilding—illustrates the integration of economic and military cooperation in shaping the bilateral relationship.

From a technical standpoint, nuclear-powered submarines offer several advantages over their conventional counterparts. They can operate submerged for extended periods without surfacing, significantly reducing detection risk. Their higher speeds and enhanced endurance make them effective for both defensive and offensive operations, including intelligence gathering, reconnaissance, and strategic deterrence. Analysts believe that the submarines could also be equipped with advanced weaponry, including torpedoes and cruise missiles, further bolstering South Korea’s maritime security posture.

While the initiative is primarily defensive, it has drawn international attention given the sensitive nature of nuclear-powered military vessels. South Korea has consistently emphasised that the submarines are not intended for nuclear weapons deployment but rather to strengthen the country’s ability to respond to North Korean provocations and ensure maritime security. Nevertheless, the move has the potential to influence regional naval balances, particularly in the context of rising tensions between the US, China, and North Korea.

Historically, South Korea’s navy has relied on conventional diesel-electric submarines to patrol its territorial waters and protect vital shipping lanes. These vessels, while effective for coastal defence, are limited in range and require frequent surfacing for battery recharging, which reduces operational stealth. The transition to nuclear-powered submarines will allow Seoul to extend its strategic reach, maintain continuous underwater patrols, and deter potential adversaries from challenging South Korean sovereignty.

The US-South Korea submarine programme also aligns with broader American strategic objectives in the Indo-Pacific region. By supporting allied nations with advanced military technology, the United States strengthens regional deterrence and reinforces the credibility of its security commitments. This approach is particularly relevant in the context of North Korea’s ongoing nuclear developments and China’s growing naval capabilities. Analysts suggest that the deployment of South Korean nuclear-powered submarines will complement US naval operations in the region, enhancing overall maritime security and reinforcing joint deterrence efforts.

In addition to strategic considerations, the programme will have economic and industrial implications. The construction of nuclear submarines involves advanced shipbuilding technologies, nuclear fuel handling, and specialized training for crews and maintenance personnel. South Korean shipyards, particularly those under large conglomerates like Hanwha, are expected to benefit from increased investment, technological upgrades, and the creation of highly skilled jobs. The collaboration with US firms will also facilitate technology transfer and enhance South Korea’s indigenous defence manufacturing capabilities.

The agreement represents a milestone in South Korea’s defence policy and underscores the country’s evolving military posture. By developing nuclear-powered submarines with US assistance, Seoul aims to achieve a credible deterrent against North Korea while asserting its strategic presence in the region. The vessels will serve as a potent symbol of South Korea’s commitment to safeguarding its sovereignty and maintaining stability on the Korean Peninsula.

While the programme is still in its early stages, defence experts emphasize the long-term significance of the initiative. Nuclear-powered submarines are complex and costly to build, requiring rigorous testing, crew training, and secure handling of nuclear materials. Nevertheless, South Korea’s experience with civilian nuclear technology, combined with US support for fuel sourcing and technical guidance, positions the country to successfully implement the project.

The announcement has been welcomed domestically as a demonstration of South Korea’s growing military self-reliance and strategic foresight. Citizens and policymakers alike view the submarines as essential to countering emerging threats from North Korea and maintaining a credible deterrent against regional instability. At the same time, officials are mindful of the need for careful communication to avoid escalating tensions unnecessarily with neighbouring states, including China, which has closely monitored developments on the Korean Peninsula.

In summary, the US-South Korea nuclear submarine agreement represents a convergence of strategic, economic, and technological priorities. The programme strengthens bilateral security cooperation, enhances South Korea’s maritime capabilities, and signals a credible deterrent to North Korea. It also underscores the United States’ commitment to supporting allies in the Indo-Pacific region amid evolving regional security challenges. As construction progresses and crews are trained, the new submarines are expected to play a central role in South Korea’s defence strategy for decades to come.