South Korea's Defense Minister Wants Nuclear Weapons. Washington Says No.

South Korea's defense minister told parliament Tuesday that his government is now seriously considering developing its own nuclear weapons, marking the first time a sitting cabinet member has publicly endorsed what was until recently a taboo position in Seoul — and setting up a direct confrontation with Washington over the future of security on the Korean Peninsula.

For Park Jin-woo, a 58-year-old electronics shop owner in Daegu whose father fought in the Korean War, the minister's words were a relief. "We cannot trust America forever," he said Wednesday outside his store, two blocks from a US military base. "They will leave when it suits them. We need our own bombs."

Defense Minister Kim Yong-hyun's comments, delivered during a National Assembly session, reflect a seismic shift in South Korean strategic thinking. Public support for indigenous nuclear weapons has surged to 76 percent, according to a February 2026 poll by the Asan Institute for Policy Studies, up from 54 percent in 2022. The change is driven by three converging anxieties: North Korea's accelerating weapons programme, which now includes tactical nuclear warheads small enough to fit on short-range missiles; uncertainty about whether Washington would risk Los Angeles to defend Seoul; and the political instability that followed President Yoon Suk Yeol's aborted martial law declaration in December 2024, which has left South Korea's leadership weakened just as regional threats intensify.

The Arsenal Next Door

North Korea conducted its seventh nuclear test on January 12, 2026, according to seismological data analysed by the Comprehensive Nuclear-Test-Ban Treaty Organization. The 18-kiloton underground blast at the Punggye-ri test site was followed three weeks later by the unveiling of what state media called a "tactical nuclear warhead" small enough to be mounted on the KN-23 short-range ballistic missile, which can reach any target in South Korea within seven minutes of launch.

Kim Jong Un now commands an estimated arsenal of 50 to 60 nuclear warheads, according to assessments published in March 2026 by both the Stockholm International Peace Research Institute and South Korea's National Intelligence Service. That is triple the number North Korea possessed in 2020. The regime has also demonstrated intercontinental ballistic missiles capable of reaching the continental United States, testing the Hwasong-18 solid-fuel ICBM four times between November 2025 and March 2026.

The speed and sophistication of this expansion has shaken Seoul's confidence in what Washington calls "extended deterrence" — the promise that America's nuclear umbrella will protect its allies. "The question is no longer whether North Korea has the bomb," said Choi Kang, vice president of the Asan Institute. "It is whether we believe the United States would trade Seattle for Seoul. And that belief is eroding."

The Alliance Under Strain

The US-South Korea alliance, formalised in the 1953 Mutual Defense Treaty, has been the bedrock of security on the peninsula for seven decades. But cracks have appeared. During his first term, President Donald Trump called the alliance "obsolete" and demanded Seoul pay $5 billion annually for the stationing of 28,500 US troops — a fivefold increase. Though President Biden restored traditional terms, Trump's return to influence within the Republican Party has revived doubts about American reliability.

Those doubts deepened after December 3, 2024, when President Yoon declared martial law in a bizarre late-night televised address, only to rescind it six hours later under pressure from the National Assembly. Yoon survived two impeachment votes but has governed since as a lame duck, his approval rating at 23 percent according to Gallup Korea. The political chaos came at precisely the moment when South Korea needed decisive leadership to manage escalating threats from Pyongyang and navigate a fraught relationship with Beijing, which opposes both US missile defenses in South Korea and any move toward a South Korean nuclear capability.

Washington's response to Minister Kim's nuclear comments was swift and negative. State Department spokesperson Laura Chen told reporters Tuesday that "the United States remains firmly opposed to nuclear proliferation on the Korean Peninsula or anywhere else" and that extended deterrence commitments to Seoul are "ironclad." But the firmness of that language has not dispelled South Korean skepticism. A March 2026 survey by Seoul National University's Institute for Peace and Unification Studies found that only 38 percent of South Koreans believe the US would use nuclear weapons to defend them in the event of a North Korean attack.

The Technical Path

South Korea possesses the technical capability to build nuclear weapons quickly. It operates 24 nuclear power reactors and has a sophisticated civilian nuclear programme. Its stockpile of plutonium, under International Atomic Energy Agency safeguards, totals approximately 40 metric tons — enough, if reprocessed, for hundreds of warheads. Defense analysts estimate Seoul could produce a functional nuclear device within 18 months of a political decision to do so.

The country is also a signatory to the Treaty on the Non-Proliferation of Nuclear Weapons, which it joined in 1975. Withdrawing from the NPT would trigger automatic sanctions and international condemnation. North Korea withdrew from the treaty in 2003, three months before conducting its first nuclear test. South Korea's path would be diplomatically smoother than Pyongyang's, given its democratic credentials, but still fraught: China would almost certainly impose economic penalties, and Japan — which relies on the same US extended deterrence guarantee — would face domestic pressure to follow suit, potentially triggering a Northeast Asian arms race.

"If Seoul goes nuclear, Tokyo will reconsider," said Narushige Michishita, director of the Security and International Studies Program at the National Graduate Institute for Policy Studies in Tokyo. "And if Tokyo reconsiders, Beijing will expand. We are talking about the unravelling of the entire regional order."

What Washington Offers Instead

To head off South Korea's nuclear ambitions, Washington has doubled down on visible demonstrations of extended deterrence. In February 2026, a US Navy Ohio-class ballistic missile submarine made a rare port call in Busan, the first such visit since 1981. The Pentagon also deployed additional Patriot missile batteries and agreed to expand joint US-South Korea military exercises, including annual drills simulating nuclear contingencies.

The White House has also revived the Nuclear Consultative Group, established in April 2023 but dormant for much of 2024 and 2025. The NCG gives South Korean officials a formal role in US nuclear planning, including tabletop exercises and intelligence-sharing on North Korean capabilities. But critics argue it remains largely symbolic. "Consultation is not control," said Park Won-gon, professor of North Korean studies at Ewha Womans University. "Seoul wants assurance that if Pyongyang launches, Washington responds immediately. The NCG does not provide that guarantee."

The Biden administration has resisted South Korea's request for NATO-style "nuclear sharing," in which US warheads would be stationed on South Korean soil under dual control. Such an arrangement exists in five European countries — Belgium, Germany, Italy, the Netherlands, and Turkey — but the Pentagon considers the Korean Peninsula too volatile and the risk of inadvertent escalation too high. Introducing US nuclear weapons to the South would also likely trigger a Chinese military buildup and provide North Korea with a pretext for further weapons tests.

The Domestic Politics of the Bomb

Defense Minister Kim's statement did not represent a formal shift in government policy — President Yoon has not endorsed indigenous nuclear development — but it reflects growing pressure from both the political right and the public. Former President Park Geun-hye, ousted in 2017, recently published an op-ed in the Chosun Ilbo calling nuclear weapons "a necessity, not a choice." Even centrist politicians, wary of alienating Washington, have begun hedging. Lee Jae-myung, leader of the opposition Democratic Party, told reporters in March that while he opposes withdrawal from the NPT, "all options must remain on the table."

The domestic political calculation is complicated by South Korea's next presidential election, scheduled for March 2027. Yoon cannot run again due to term limits, and polls show the race wide open. A candidate who campaigns on nuclear sovereignty could mobilise nationalist sentiment and peel away voters frustrated with perceived American indifference. That makes the next 11 months a particularly dangerous window: a lame-duck president, an emboldened opposition, and a defense minister willing to say what was once unsayable.

What Comes Next

Washington now faces a strategic dilemma. Pressuring South Korea too hard risks pushing Seoul toward a nuclear breakout it can technically achieve and politically justify. Accommodating Seoul's demands — through nuclear sharing or other visible commitments — risks provoking China and undermining global nonproliferation norms. And doing nothing ensures that the current drift continues, with trust eroding and public opinion hardening in favour of an indigenous deterrent.

Some analysts argue the solution lies not in Seoul or Washington but in Beijing, which retains significant leverage over North Korea despite recent strains. If China could broker a freeze on Pyongyang's weapons programme — even a partial one — it might reduce South Korean threat perceptions enough to take nuclear weapons off the table. But Beijing has shown little appetite for pressuring Kim Jong Un, especially as US-China relations deteriorate over Taiwan, trade, and technology controls.

For now, the debate in Seoul continues. Minister Kim's comments were condemned by some opposition lawmakers as "reckless" and praised by others as "overdue honesty." The National Assembly will hold hearings on nuclear policy in May. Meanwhile, North Korea shows no sign of slowing its weapons development. On March 28, state media released footage of what it claimed was a submarine-launched ballistic missile test — the fifth such test since January.

Back in Daegu, Park Jin-woo watched the latest North Korean missile footage on his phone and shook his head. "My father fought so we could be free," he said. "Now we are free, but we are not safe. If America will not protect us, we must protect ourselves."