At the heart of the Pacific, a diplomatic and strategic debate is brewing over the future of nuclear-powered submarines in East Asia. The United States Navy, long a dominant force in the region, is now openly discussing the potential for both South Korea and Japan to acquire nuclear submarines—but with starkly different expectations and warnings for each ally.
On September 9 and 10, 2026, at the Pearl Harbor-Hickam Joint Base in Hawaii, a senior US Navy official addressed a gathering of Asian and Pacific journalists, laying out Washington’s evolving stance. According to Hankyoreh and YTN, the official stated, “The United States supports South Korea’s acquisition of nuclear-powered submarines,” but quickly added a caveat: “If South Korea’s operations do not extend beyond the Korean Peninsula, nuclear submarines are not necessary. South Korea must find a valid reason for having them.” The official was adamant that acquiring such costly and complex vessels merely as a “status symbol” would be a mistake.
This position was echoed and expanded upon in reports by Nikkei, Yomiuri Shimbun, and Yonhap News. The US Navy’s message is clear: for South Korea, nuclear submarines only make sense if Seoul intends to expand its naval footprint beyond traditional North Korea deterrence, particularly into broader Indo-Pacific operations where China’s growing maritime influence looms large. As the official put it, “If South Korea does not intend to operate beyond its nearby waters, nuclear submarines are unnecessary.”
The US Navy’s Chief of Naval Operations, Admiral Darryl Cuddel, has previously weighed in on this issue. During a visit to South Korea in November 2025, Admiral Cuddel remarked, “It is a natural expectation that South Korea’s nuclear submarine will be used to deter China.” This sentiment, according to Maeil Business News and YTN, underscores the strategic calculus at play: Washington wants its allies to shoulder more responsibility in counterbalancing Beijing’s assertiveness in the region.
Meanwhile, the conversation around nuclear submarines is also heating up in Japan. The same US Navy official told Yomiuri Shimbun and Kyodo News that Japan should “consider acquiring nuclear-powered submarines,” citing Japan’s existing nuclear power infrastructure as a technical foundation. “Japan already operates nuclear power plants, so technically it is possible to build nuclear submarines,” the official said. This is not a trivial endorsement. Japanese conservative parties, including the right-leaning Nippon Ishin no Kai, are pushing for nuclear submarine acquisition as part of upcoming revisions to Japan’s core national security documents. They argue that such vessels are essential for long-range and long-duration missions, especially with the growing missile threat in the region.
However, the debate in Tokyo is far from settled. Cost, crew recruitment, and constitutional constraints—especially Japan’s long-held Non-Nuclear Three Principles, which prohibit possession, manufacture, or introduction of nuclear weapons—remain significant hurdles. The ruling Liberal Democratic Party has so far only recommended studying “next-generation propulsion” in security documents, carefully avoiding direct mention of nuclear submarines. Nonetheless, as Kyodo News reports, some lawmakers have begun to question whether the “no introduction” principle should be re-examined.
The US Navy’s stance reflects a nuanced approach to its two key allies. For Japan, the message is one of encouragement—leveraging technical capability and potentially deepening defense cooperation. The official even expressed hope for “cooperation with Japan to enhance US military shipbuilding and maintenance capabilities,” a nod to the challenges the US faces in maintaining sufficient naval presence in the Indo-Pacific. For South Korea, however, the bar is set higher. The acquisition of nuclear submarines must be justified by a willingness to operate far beyond the peninsula, with an eye on deterring China and supporting regional security goals.
There are practical considerations, too. Nuclear submarines are expensive, complex, and require specialized crews. “Nuclear submarines cost a lot,” the US Navy official reminded reporters, “and if South Korea is pursuing them for national prestige, that would be the wrong reason.” The official also referenced the Trump administration’s “bridge plan,” which involved building ships abroad before expanding domestic production, as a necessary—if slow—step to address US shipbuilding capacity shortages. The official quipped, “Is it a matter of being late or never doing it at all?”
Amid these strategic calculations, the specter of North Korea remains ever-present. The US official acknowledged concerns over Pyongyang’s submarine capabilities, particularly with possible Russian support. “Possession does not equal operational proficiency,” the official noted, adding that while Russia’s assistance is worrisome, “we have not yet seen anything that greatly concerns us.” It’s a reminder that, in the complex chess game of regional security, numbers alone do not guarantee power—training, doctrine, and operational experience matter just as much.
South Korea, for its part, has recently informed the International Atomic Energy Agency (IAEA) of its intention to begin discussions on nuclear submarine development. As a signatory to the Nuclear Non-Proliferation Treaty (NPT), Seoul is exploring exceptions that allow the use of nuclear material for military (but non-weapon) purposes, a move that will require careful diplomacy and technical oversight.
Amid growing global security uncertainties, there is a sense—especially in Washington—that a South Korean nuclear-powered submarine could enhance combined US-ROK military power. The US official praised South Korean shipbuilding companies as “world-class,” expressing confidence that their expertise would contribute to both US and allied naval capabilities. “South Korean shipbuilders are the best in the world,” the official said, highlighting the potential for deeper industrial cooperation.
Yet, the path forward is far from straightforward. For South Korea, the decision to acquire nuclear submarines is entangled with questions of national ambition, alliance expectations, and the realities of regional power politics. For Japan, the debate is just beginning, with technical capability running up against political and societal taboos rooted in postwar pacifism. And for the United States, the challenge is to encourage its allies to take on greater roles—while ensuring that every step taken is grounded in clear strategic logic, not just the allure of prestige or symbolism.
As the waves of the Pacific lap against the docks at Pearl Harbor, it’s clear that the future of undersea power in East Asia will be shaped as much by careful calculation as by technological prowess. The choices made in Seoul and Tokyo in the coming months will ripple far beyond their shores, shaping the balance of power in the world’s most dynamic—and contested—region.