NOVEMBER 17 — In a development that might reshape the maritime strategic balance of the North-east Asia’s maritime balance, the US has given political approval for South Korea to pursue a nuclear-powered submarine programme. It is a breakthrough long sought-after by Seoul. Although constrained by non-proliferation rules, the decision allows nuclear technology cooperation and fuel supply for reactor system made by South Korea. it is a rare occasion that Washington willing to extend elements of its tightly held naval technology.

For Seoul, this is beyond an industrial or military project: it is a strategic maturity and confidence that affirming South Korea as a major maritime power capable of projecting presence beyond its coastal water.

It also raises difficult questions about regional reactions, especially from Beijing and Pyongyang, which already interpreted this as another layer of US–South Korea deterrence integration.

The approval from the Trump administration builds on years of high-pace progress in domestic defence industries. KSS-III Dosan Ahn Changho-class submarines, which are indigenous design of South Korea, equipped with Air-Independent Propulsion (AIP) and vertical launch systems, have demonstrated world-class capability of local shipyards such as HD Hyundai Heavy Industries and Hanwha Ocean.

Dream of transitioning from diesel-electric to nuclear propulsion is not surprising for South Korea.

A nuclear-powered submarine would grant the Republic of Korea Navy (ROKN) unprecedented endurance, stealth, and patrol range, enabling continuous underwater presence beyond the East China Sea and the wider Indo-Pacific. Beyond the technical triumph, the programme also reflects Seoul’s broader aspiration for strategic autonomy in securing its sea lanes, balancing regional power, and reinforcing deterrence without depending on foreign fleets.

The US-South Korea nuclear submarine deal go beyond the AUKUS pathway, in which Australia will deploy nuclear submarines in the Indian Ocean and South Pacific in long term trajectory. The move will distribute undersea patrol responsibilities among like-minded partners and complicating any single navy ability to dominate vital maritime approaches.

Together with persistent US submarine presence from south of Japan down toward the Philippines, a South Korean nuclear submarine force is expected to fill a crucial gap in the East Asian littoral, boosting collective maritime awareness and raising the operational cost for Beijing of any coercive action.

South Korea not only receiving nuclear submarine technology, but also partnering with the US to revive the shipbuilding industry in the US.

This initiative carries the same strategic logic: to further strengthening trusted partnerships, advance undersea technologies, and building a coherent deterrent network that helps preserve stability across the Indo-Pacific.

Now, let’s turn to a wider context, the emerging US–South Korea nuclear submarine cooperation fits neatly into a larger American strategy of pressure and competition.

The plan of President Trump to restart nuclear testing is not an isolated act of defiance but a calculated signal, it is designed to challenge China’s resolve and to lure Beijing into re-opening its nuclear testing programme.

When combined with AUKUS and the strengthening of allied undersea capabilities in both hemispheres, Washington is effectively tightening a strategic circle around China. The underlying logic is to push Beijing into an expensive cycle of technological catch-up and arms demonstration that could expose the limits of its economy and erode its diplomatic narrative of restraint.

Hence, the nuclear submarine programme of South Korea is not just a naval milestone, but a carefully staged geopolitical chess to test China’s endurance in the next phase of great-power rivalry.

Admiral Daryl Caudle, Chief of US naval operations confirmed it.

So, why would Washington willingly stoke this fire?

The answer is as much economic as military. From this perspective, the move is premised on a simple asymmetry: Beijing will politically-compelled to respond to high-profile nuclear signalling, and full-scale testing is both technically demanding and financially costly.

For an economy that still facing strong structural headwinds, diverting huge capital and skilled labour into renewed nuclear tests would be a painful drain. By contrast, Trump administration, who is confident in its ability in attracting thousands of billions of foreign investment inflows, as well as the capability in mobilising private capital quickly, is arguably better placed to absorb the geopolitical and fiscal shocks of escalatory signalling.

In short, Trump administration is gambles on forcing China into an expensive catch-up cycle while the US leans on economic buffers that Beijing lacks. This is a form of strategic statecraft that weaponises fiscal resilience as much as military might.

One unresolved issue in the nuclear submarine discussion lies in the reactor fuel.

In the AUKUS arrangement, Australia will receive highly enriched uranium (HEU) fuel, which is the same grade as those in US and uk submarines, typically above 90 per cent U-235.

In contrast, Seoul has not yet been told whether it will be granted access to HEU or limited to low-enriched uranium (LEU), typically below 20 per cent.

The decision is pivotal.

Granting HEU would represent unprecedented US trust and a near-AUKUS level of technology transfer, instantly placing submarines of South Korea among the elite class of global navies.

Denying it, on the other hand, would restrict the autonomy of South Korea, forcing it to rely on periodic refuelling, a significant operational disadvantage for long-endurance missions in the Pacific.

Technically, HEU fuel enables compact, smaller and quieter reactors that can operate for decades without maintenance, which is ideal for stealth and deep-ocean patrols. LEU reactors are bulkier and require mid-life refuelling, but it is less sensitive under international non-proliferation rules.

It can be interpretated that, the enrichment level is not merely an engineering parameter; it is a signal of strategic trust and confidence. It is also a measure of how far the US is willing to extend its nuclear technology umbrella.

For Washington, granting HEU to Seoul risks opening a precedent that other close allies, such as Japan or even Nato partners might demand. For Seoul, acceptance of LEU would mean more indigenous R&D required, but greater freedom from international scrutiny under the Non-Proliferation Treaty (NPT).

In fact, this submarine initiative is not something from nowhere, it is a calculated move that advances strategic aims of both Seoul and Washington respectively.

For Seoul, it accelerates military-technical capability, deepens high-value supply chains at home, and cements a more credible undersea deterrent. For Washington, this is beyond the immediate industrial payoff of re-creating shipbuilding jobs on US soil.

In addition, the arrangement also creating strategic flexibility, allowing the Washington to free up some resources for other theatres while imposing costly choices on Beijing.

In conclusions, the submarine initiative pressures China to spend or respond. So, will Beijing reopen nuclear testing to signal parity, or will it seek asymmetric counters such as exporting nuclear submarine technology to cultivate its friendly proxies?

The ball is now squarely in China’s court — and its next move will help determine whether the Indo-Pacific enters a costly era of escalation or a tense but managed balance.

* Phar Kim Beng is Professor of Asean Studies and Director, Institute of International and Asean Studies (IINTAS) International Islamic University Malaysia; Jitkai Chin has a PhD, PEng, Department of Chemical Engineering, Universiti Teknologi Petronas, and an expert committee member of Centre of Regional Strategic Studies (CROSS)

** This is the personal opinion of the writer or publication and does not necessarily represent the views of Malay Mail.