What if South Korea got a nuclear bomb?
An America First world will force allies to face uncomfortable questions
SOUTH KOREAN dramas keep millions of viewers around the world on edge. The country’s next thriller may be an explosive political spectacle: South Korea learns to love the bomb.
The scenario is closer to a reality show than the science fiction it may once have seemed. South Korea has toyed with going nuclear in the past. The idea has gone from fringe to mainstream in recent years. Even the country’s president, Yoon Suk Yeol, mused openly about South Korea building its own nukes in early 2023. Public support is high, fuelled in part by North Korea’s growing nuclear arsenal: polls now show that some 70% of South Koreans think their country should have nuclear weapons (see chart). “Without them, South Korea won’t have a chance to fight off the North,” says Kim Young-sik, a former district head on Yeonpyeong Island, a flashpoint near the maritime border.
Under President Joe Biden, America has tried to reassure its unsettled ally. After Mr Yoon’s comments last year, America and South Korea signed a declaration restating their commitment to “extended deterrence”, America’s promise to shield allies with its nuclear arsenal. A new consultative group brought South Korea closer to America’s nuclear planning; an American nuclear-armed submarine docked in South Korea last year for the first time since 1981. In recent statements, Mr Yoon has talked down the chances of going nuclear.
But if Donald Trump, who in the past threatened to pull American troops out of South Korea, is re-elected, the calculus will change. Many will ask if America can be trusted to defend South Korea, especially now that North Korea’s intercontinental missiles put American cities at risk. “If Trump is president in America, it’s all the more reason for us to have nukes,” says Mr Kim. “I’m afraid that America won’t take any action that will cost it anything.” It is an acute form of a fear all American allies will face under an America First president.
South Korea has many reasons not to go for the bomb. North Korea, China and Russia would respond with economic pressure or sabre-rattling, and perhaps with outright aggression. Exiting the Nuclear Non-Proliferation Treaty (NPT) could damage South Korea’s international standing. Its trade-dependent economy would suffer if sanctions are imposed. Elites are less gung-ho about going nuclear than average voters, who may not be as aware of the risks: one-third of 175 South Korean experts and officials surveyed this year by CSIS, an American think-tank, support an independent nuclear arsenal.
Mr Trump may not prove as disruptive as many fear. The relationship with South Korea enjoys bipartisan support in America. Congress could complicate plans to move troops by refusing to fund their relocation. Camp Humphreys, south of Seoul, is America’s biggest overseas military installation and would be impossible to replicate elsewhere in Asia. Mr Trump may be satisfied if South Korea pays much more to host America’s troops—and submitting to his notion of alliances as a protection racket may prove simplest for South Korea.
But Mr Trump could also stoke doubts about America’s commitment, fuel fears about entangling South Korea in a broader war with China, or seek a deal with Kim Jong Un, North Korea’s tyrant. Mr Trump halted large-scale military exercises with South Korea during previous negotiations with Mr Kim, and, say former officials, had to be stopped from withdrawing troops from South Korea. In a second administration staffed with loyalists, Mr Trump would have a freer hand. A mere tweet might dent confidence in America’s extended deterrence. In the CSIS survey, more than half of the South Korean experts opposed to going nuclear say their support would increase if America were led by an America First president.
There is a clear prequel to this show. In the early 1970s, with America facing defeat in Vietnam, Richard Nixon pulled out 20,000 of the 63,000 American troops stationed in South Korea and asked allies in Asia to take more responsibility for their own security. “There was huge uncertainty about the staying power of the United States,” says Richard Lawless, who served as a CIA officer in Seoul at the time. North Korea did not have nuclear weapons, but it outgunned the South in conventional terms. Park Chung-hee, then South Korea’s president, launched a secret effort to obtain nuclear-weapons technology. When Mr Lawless helped uncover the programme, American officials used pressure and security assurances to block it. South Korea joined the NPT in 1975.
Sweet charity
This time America’s role may be different. Mr Trump might acquiesce to or even encourage South Korea’s going nuclear, seeing extended deterrence as a charitable act rather than a cold calculation of American interests. Visiting Seoul in recent months, former officials close to Mr Trump have signalled unprecedented openness to the idea. Mike Pompeo, Mr Trump’s secretary of state and CIA director, was asked about South Korea’s developing its own nuclear capabilities. “There’s no reason we should object to that,” he answered, calling it “rational”, given North Korea’s arsenal.
South Korea’s nuclear script would resemble earlier episodes of proliferation in some respects and be singular in others. In “Seeking the Bomb”, Vipin Narang, a political scientist who until recently oversaw nuclear policy at the Pentagon, lays out four strategies that potential proliferators pursue: hedging (putting pieces in place to keep the nuclear option available); sprinting (running towards nuclear weapons quickly); sheltered pursuit (acquiring them with a nuclear superpower’s protection); and hiding (attempting to do so in secret).
South Korea currently practises a form of hedging. Under Park’s military dictatorship, it tried hiding. It could attempt that again. But it would be much harder in today’s wired, raucous democracy. “There are too many eyes watching now,” says Lee Sang-hyun of the Sejong Institute, a think-tank in Seoul. “If South Korea goes nuclear it would be public, with lots of noise.” It would, in short, make a run for it, either with or without America’s protection. Many experts and diplomats reckon that South Korea could race to build its first nuclear weapon in as little as one year.
Since the 1970s, South Korea has developed a world-class civil-nuclear industry with a reputation for engineering prowess. It has 26 reactors across the country; South Korean firms are constructing nuclear plants in the United Arab Emirates and the Czech Republic. “By now the physics and the science have been done. What you need is good engineering,” says Siegfried Hecker, who used to run America’s nuclear laboratory at Los Alamos. “And they’re really good in all aspects of engineering all things nuclear.”
What South Korea lacks is the raw material of a bomb: highly enriched uranium or plutonium from reprocessed nuclear fuel. The country’s nuclear industry does not currently reprocess spent fuel, and it imports the enriched uranium used in civilian reactors. South Korea would have to build new facilities to reprocess or enrich at scale. But it has stockpiles of spent fuel from its civilian reactors, which, while not ideal, could be used to make weapons. In a 2015 paper, Charles Ferguson, then the president of the Federation of American Scientists, wrote that South Korea has enough material for over 4,000 bombs.
South Korea could stop the show at enrichment. That would bring its nuclear capabilities in line with Japan’s. (To South Korea’s chagrin, America gives Japan special permission to reprocess spent fuel and enrich uranium, ostensibly to facilitate fuel recycling and to help with nuclear-waste management.) This middle-ground option would allow South Korea to shrink the time needed to build weapons in the future, without crossing the proliferation line.
But South Korea is well-placed to go for full weaponisation. “They are already a missile power in their own right,” says Ankit Panda of the Carnegie Endowment for International Peace, another American think-tank. “That’s unprecedented in terms of other proliferators.” South Korea has advanced short and mid-range ballistic missiles that could be equipped with nuclear warheads; it is the only non-nuclear-armed country in the world to have developed submarine-launched ballistic missiles. It would have to come up with new command-and-control systems for nukes, as well as a doctrine for their use.
Test cases
Testing would pose a big challenge. South Korea is one-third the size of New Mexico, and densely populated. It would be hard to find a secluded site, or a province willing to tolerate the risks of radiation release from an underground-test facility. (North Korea’s underground-test site is more remote, and its people have no say over the risks their rulers subject them to.) An atmospheric test would be provocative—China carried out the most recent in 1980. Computer simulations have become sophisticated, but would be unsatisfactory to any bomb designer.
Even after completing its first nuclear devices, South Korea could not simply halt there. North Korea is believed to have dozens of nuclear weapons; its arsenal is already projected to grow into the hundreds by the end of this decade. A South Korean nuclear programme would probably prompt the North to accelerate its own; Russia might help it. While South Korea would not need to match North Korea bomb for bomb, it would have to be sure it could strike back with nuclear weapons after being attacked with them first.
South Korea would be vulnerable during its breakout. America could extend its nuclear umbrella in the meantime. But tensions would run high. North Korea could be counted upon to sabre-rattle. The probability of accidental escalation would rise. The possibility of a North Korean pre-emptive strike on South Korea, while unlikely, cannot be ruled out.
Though polls indicate widespread support, plenty of domestic critics would speak out. Conservatives, who control the presidency until at least 2027, would be more likely to support an independent nuclear arsenal. Some in the opposition Democratic Party (DP), which now controls the National Assembly, might be in favour, either as a matter of necessity or as a means of achieving long-sought autonomy from America. Yet others would oppose it. “The nuclear option is a one-way ticket—if we go forward, it’s impossible to go back,” says Wi Sung-lac, a former ambassador and newly elected parliamentarian for the DP. Even if Mr Trump allows South Korea to go nuclear, “what happens if a traditional American administration returns after Trump and says no?”.
Going nuclear would amount to a drastic costume change for South Korea. Instead of being known globally for pop music and kimchi, it would be defined by the bomb. International sanctions might prove limp. America could veto any punishment at the United Nations. South Korea could try to exit the NPT legally, under an article that allows members to withdraw if “extraordinary events” threaten its “supreme interests”. Partners in the West might be sympathetic to its case.
Some restrictions would be triggered nonetheless. The Nuclear Suppliers Group (NSG), an international body which oversees fissile material for the civil industry, would probably call on members to cut off co-operation with South Korea. America could push for an exemption at the NSG, as it did for India. But without one, South Korea’s nuclear export business would melt down and its domestic reactors would sit idle, knocking some 30% of South Korea’s electricity production offline. If South Korea were to test a nuclear device, American law mandates an end to arms transfers and exports of dual-use technologies.
China could impose its own crippling restrictions—probably far harsher than the damaging measures that followed the deployment of an American missile-defence system in South Korea in 2017. Some 20% of South Korea’s exports flow to China, and South Korea relies heavily on China for many key components and materials.
If South Korea goes nuclear, it will prompt others who depend on American extended deterrence to contemplate sequels of their own. Japan might overcome its long-standing aversion to nuclear weapons. “It’s not a question of letting one cat out of the bag—all the cats come out of the bag,” says Mr Lawless, who later served as the Pentagon’s top official for Asia.
Would nuclear weapons really make South Korea safer? Advocates argue that South Korea needs them to counter the North: though it has stronger conventional forces, only the special terror of nuclear weapons can create the psychological effect necessary to deter. Besides, if both sides have the weapons, it may prove easier to negotiate mutual disarmament.
Detractors counter that the peninsula will inevitably become a much more dangerous place if South Korea goes nuclear. “What kind of peace is it if both have nukes?” argues Mr Lee. Rather than enabling disarmament, “there will be an arms race”. Untested leaders on both sides of the border will have their fingers on the nuclear trigger. The finale of this drama could see them stumbling into Armageddon. ■
This article appeared in the Asia section of the print edition under the headline “Extended uncertainty”