U.S. President Donald Trump made headlines last October when he announced<\/a> he had given South Korea approval to build nuclear-powered submarines. It\u2019s unclear whether the United States will supply the nuclear fuel or permit South Korea to enrich its own, but the latter option would effectively give South Korea the technical capacity to produce nuclear weapons quickly\u2014within a matter of months\u2014if it so chooses, a condition known as nuclear latency.<\/p>\n To do this, Trump would theoretically need Congress to revise the bilateral U.S.-Korea nuclear cooperation agreement, known as the 123 Agreement<\/a>. Last updated in 2015, this agreement allows South Korea to enrich uranium up to 20 percent and pursue pyroprocessing for civilian purposes with U.S. consent. However, it explicitly prohibits enriching or reprocessing U.S.-origin nuclear materials for military use, a category that includes fuel for nuclear-powered submarines.<\/p>\n<\/p><\/div>\n U.S. President Donald Trump made headlines last October when he announced<\/a> he had given South Korea approval to build nuclear-powered submarines. It\u2019s unclear whether the United States will supply the nuclear fuel or permit South Korea to enrich its own, but the latter option would effectively give South Korea the technical capacity to produce nuclear weapons quickly\u2014within a matter of months\u2014if it so chooses, a condition known as nuclear latency.<\/p>\n To do this, Trump would theoretically need Congress to revise the bilateral U.S.-Korea nuclear cooperation agreement, known as the 123 Agreement<\/a>. Last updated in 2015, this agreement allows South Korea to enrich uranium up to 20 percent and pursue pyroprocessing for civilian purposes with U.S. consent. However, it explicitly prohibits enriching or reprocessing U.S.-origin nuclear materials for military use, a category that includes fuel for nuclear-powered submarines.<\/p>\n But two weeks after Trump\u2019s initial announcement, the White House released a fact sheet<\/a> that laid out a way to bypass Congress altogether. \u201cConsistent with the bilateral 123 Agreement and subject to U.S. legal requirements,\u201d it said, \u201cthe United States supports the process that will lead to the [Republic of Korea\u2019s] civil uranium enrichment and spent fuel reprocessing for peaceful uses.\u201d Unlike authorizing nuclear-powered submarines, granting South Korea consent for developing those technologies for civilian purposes faces no immediate legal barriers and does not require Congressional approval.<\/p>\n Though plenty of uncertainties remain, if the Trump administration continues down this path, it would pave the way for South Korea\u2019s nuclear latency. The key question, then, is whether Washington should<\/em> support this development. However provocative this may sound, my answer is \u201cyes\u201d\u2014not because nuclear latency comes without risk, but because all the alternatives may be even worse for U.S. interests.<\/p>\n Although South Korea\u2019s acquisition<\/span> of enrichment or reprocessing technology would not, in itself, violate the Nuclear Non-Proliferation Treaty (NPT), these capabilities are inherently proliferation-prone. They enable a state to produce fissile material, which is the most technically demanding step in building a nuclear weapon. Once mastered, such capabilities dramatically shorten the timeline and lower the political and economic costs of nuclear armament.<\/p>\n For this reason, Washington has long restricted recipients of its civilian nuclear assistance from pursuing enrichment and reprocessing technologies without explicit U.S. consent. This reluctance stems from the potential negative consequences for the global nonproliferation regime. If South Korea acquires these capabilities, other countries, such as Saudi Arabia and Turkey, may seek to do the same, and U.S. efforts to prevent their pursuit would inevitably provoke accusations of double standards. The wider diffusion of nuclear latency would, in turn, make the global security environment significantly more fragile.<\/p>\n These concerns are legitimate. But the United States\u2019 alternatives are fraught as well.<\/p>\n The current approach\u2014relying on extended deterrence while restricting South Korea\u2019s nuclear options\u2014is increasingly untenable. South Koreans continue to question the credibility of U.S. security guarantees, and public support for nuclear armament remains high. Even after the 2023 Washington Declaration and the launch of the Nuclear Consultative Group, which demonstrated strong U.S. commitment to defending South Korea, support for an indigenous arsenal dipped<\/a> only briefly before rebounding to nearly 73 percent<\/a> by early 2024\u2014and rising to more than 76 percent<\/a> after Trump returned to office last year.<\/p>\n This suggests that no matter what the United States does to bolster its deterrence, it may not be sufficient to address South Korea\u2019s enduring skepticism over whether the United States would truly risk New York, Los Angeles, or Chicago to defend Seoul. That concern is becoming more acute as North Korea moves closer to possessing a reliable capability to strike the U.S. homeland. Once North Korea can credibly threaten U.S. cities, the costs and risks of defending South Korea could become too high for the United States.<\/p>\n Against this backdrop, Washington\u2019s mantra<\/a> of strengthening \u201cthe credibility of the U.S. extended deterrence commitment\u201d is unlikely to assuage South Korea\u2019s sense of insecurity.<\/p>\n \u00a0<\/strong>This option offers minimal strategic benefit. Although some in Seoul support the idea, redeploying U.S. tactical nuclear weapons is also unlikely to address South Korea\u2019s underlying strategic concerns. While such a move might create the appearance of a stronger U.S. commitment, it would remain squarely within the traditional framework of extended deterrence, with Washington retaining full operational control.<\/p>\n Given the proximity of the two Koreas, Seoul would almost certainly push for shared or even pre-delegated launch authority to account for compressed decision timelines\u2014scenarios in which a response is needed within minutes, rather than hours. Washington, however, is highly unlikely to accept such an arrangement. As a result, South Korea would remain dependent on U.S. decision-making for nuclear use, perpetuating the very vulnerability that drives its interest in nuclear autonomy.<\/p>\n Redeployment risks creating the worst of both worlds: South Korea would become more vulnerable, particularly for North Korean or Chinese strikes on nuclear storage facilities, while still lacking autonomous control over nuclear weapons.<\/p>\n At the same time, this option would impose substantial costs on the United States, both with regards to the logistical and financial burden of nuclear weapon storage and the legal concerns this would raise under Article I of the NPT, which prohibits nuclear-weapon states from transferring nuclear weapons to non-nuclear weapon states.<\/p>\n If Washington fails to address Seoul\u2019s security concerns, South Korea may choose to develop its own nuclear arsenal. Once considered unthinkable, this option could become unavoidable if the perceived costs of lacking an independent deterrent begin to exceed the costs of acquiring one. The United States would then face an unenviable choice: support (or quietly condone) South Korea\u2019s nuclearization, or sever the alliance. Neither outcome would serve U.S. interests.<\/p>\n Supporting a nuclear-armed South Korea would seriously undermine the global nonproliferation regime. Though the regime has arguably weathered North Korea\u2019s and Iran\u2019s nuclear ambitions thus far, the damage caused by a law-abiding member openly pursuing nuclear weapons\u2014with at least tacit U.S. support\u2014would be far more profound. If the principal architect and guarantor of the nonproliferation regime were seen as enabling such a move, the entire system\u2019s credibility would be gravely, perhaps irreparably, damaged. The ensuing collapse of this multilateral framework would almost certainly accelerate the spread of nuclear weapons globally.<\/p>\n On the other hand, distancing from or abandoning a nuclear South Korea would impose enormous costs on the United States. Losing a trusted ally with substantial military, economic, technological, and industrial<\/a> capabilities would significantly weaken its strategic footing in a critical region. As U.S. Forces Korea Commander Gen. Xavier Brunson recently noted<\/a>, the Korean Peninsula\u2019s geostrategic location provides cost-imposition capabilities against both Russian and Chinese forces, making the U.S. military presence there a source of \u201csignificant strategic advantage.\u201d<\/p>\n <\/a><\/p>\n \n \tA Trumpian promise may be hard to deliver. \t <\/a><\/p>\n \n \tFive questions to ask before welcoming Seoul to the nuclear weapons club. \t <\/p>\n<\/div><\/div>\n<\/div>\n<\/li>\n <\/a><\/p>\n \n \tThe global norm against nuclear proliferation is strong, but Seoul\u2019s political and economic ties are stronger. \t <\/p>\n<\/div><\/div>\n<\/div>\n<\/li>\n<\/ul><\/div>\n<\/div><\/div>\n <\/p>\n Against these alternatives,<\/span> permitting South Korea to maintain nuclear latency offers Washington several advantages.<\/p>\n First, nuclear latency could enhance stability on the Korean Peninsula by mitigating South Korea\u2019s security fears and by reducing<\/a> North Korea\u2019s incentives for limited conventional or tactical nuclear attacks. The credible prospect that South Korea could assemble nuclear weapons within months and retaliate would diminish the appeal<\/a> of aggression unless North Korea could confidently destroy the entire latent South Korean arsenal\u2014unlikely given its weak intelligence, surveillance, and reconnaissance capabilities\u2014or is willing to risk an all-out war.<\/p>\n Nuclear latency would also give South Korea leverage in future risk-reduction talks with North Korea, which has long dismissed<\/a> South Korean overtures. Counterintuitive as it may seem, a controlled degree of nuclear latency could contribute greater inter-Korean stability.<\/p>\n Second, supporting South Korea\u2019s nuclear latency could strengthen the United States\u2019 broader Indo-Pacific strategy. Acknowledging its ally\u2019s security concerns would signal trust and respect, reinforcing cohesion within the relationship. And in practical terms, preserving U.S. political support for South Korea\u2019s pursuit of nuclear-powered submarines likely requires framing them as serving a regional security role beyond deterring North Korea, since some argue<\/a> diesel-electric submarines may suffice for peninsula-focused missions. Cast as contribution to regional burden-sharing, this program, once operational, would ease pressure on U.S. submarine production capacity while strengthening deterrence against China.<\/p>\n Finally, South Korea\u2019s development of enrichment capabilities would help dilute Russia\u2019s and China\u2019s dominance of the international nuclear fuel market. Together, Russia and China currently supply more than 60 percent<\/a> of the world\u2019s low-enriched uranium (LEU) and almost all high-assay low-enriched uranium (HALEU<\/a>), essential for next-generation reactors. The United States is stepping up efforts<\/a> to expand its own nuclear fuel production, but allowing South Korea to produce LEU and HALEU at scale would further bolster energy security for the United States and its partners.<\/p>\n None of the choices facing Washington are without risk. But the question is not whether supporting South Korea\u2019s nuclear latency is ideal. It is whether the alternatives\u2014South Korean nuclear armament and losing South Korea as an ally\u2014would be better. They would not.<\/p>\n Allowing South Korea to develop controlled nuclear latency under strict safeguards and effective oversight may be the most tolerable option: one that strengthens deterrence, preserves the alliance, supports U.S. strategy in Asia, and still gives Washington time to address any potential South Korean breakout before it occurs.<\/p>\n In a world of imperfect options, the least bad choice may also be the most prudent one.<\/p>\n
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\n1. Maintain the Status Quo<\/h3>\n
\n2. Deploy Tactical Nuclear Weapons to South Korea<\/h3>\n
\n3. Support or Abandon a Nuclear South Korea<\/h3>\n
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\n <\/span>\n Can South Korea Afford the Many Costs of Nuclear-Powered Submarines? <\/h3>\n
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\n <\/span>\n South Korea Goes Nuclear. Then What? <\/h3>\n
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\n <\/span>\n South Korea Could Get Away With the Bomb <\/h3>\n
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