South Korean Nuclear Weapons Would Make Things Worse
Member Activities

South Korean Nuclear Weapons Would Make Things Worse


APLN member Van Jackson co-wrote an article with Toby Dalton, arguing that if South Korea goes nuclear, it could backfire badly and increase rather than decrease the risks and uncertainties the country would face. The original article is on the Global Asia website.

OVER THE LAST DECADE, prominent South Korean politicians, including several presidential candidates, began to speak publicly about acquiring nuclear weapons. These views have gained in popularity such that today pro-nuclear sentiments appear to be a mainstream idea. It is not uncommon to encounter arguments for nuclear weapons in Seoul among conservative factions in the National Assembly, defense analysts and editorial writers for the widest circulation newspapers.

Despite the apparent popularity of nuclear weapons in South Korea, however, there is a striking dearth of logic for how they would actually improve the country’s security.

Pro-nuclear narratives tend to concentrate on three reasons that South Korea should develop nuclear weapons. First and foremost, advocates argue that nuclear weapons would strengthen deterrence in the face of North Korea’s growing arsenal of nuclear weapons and conventional missiles. This argument seems to be based on a belief that only nuclear weapons can deter nuclear weapons, and that the US “nuclear umbrella” is no longer sufficient to deter North Korean use of tactical nuclear weapons against South Korea. Second, some pro-nuclear political elites in South Korea believe that nuclear weapons would provide insurance against abandonment by the US, fearing either US withdrawal or a decoupling of the alliance should North Korea threaten to strike US territory. And third, nuclear weapons are deemed a long-term hedge against aggression from a rising and revisionist China.

The fears driving interest in nuclear weapons are entirely understandable. There is no sugar-coating the perilous security environment that Seoul faces. North Korea’s nuclear arsenal presents a formidable challenge, and managing the risks of conflict is getting more complicated. Pyongyang’s intercontinental and short-range nuclear-capable missiles can strike targets in the US and South Korea. Coupled with a new nuclear doctrine that stresses using nuclear weapons early in conflicts, Pyongyang’s capabilities create new deterrence dilemmas for Seoul and Washington. Meanwhile, US domestic politics generate fears that the US might simply withdraw from the alliance or it could seek to entangle Seoul in a future conflict against China. And South Korean perceptions of Chinese intentions in the region are also changing, with public opinion surveys revealing beliefs that within the next decade Beijing will be the paramount threat.

But security policy ought to be based on a realistic wager about how it will improve — or at least not worsen — the circumstances that a government faces outside its borders. And that is the trouble with pro-nuclear arguments in South Korea: they fail to make a clear case for how exactly nuclear weapons would enhance Seoul’s security against contemporary and future threats. Indeed, rather than leading to peace and stability, it is more likely that acquisition of nuclear weapons would exacerbate threats and produce profoundly negative outcomes for South Korea’s security.​


Kim Jong Un’s periodic threats to use nuclear weapons against South Korea have catalyzed new fears in Seoul of North Korean nuclear coercion — specifically that Pyongyang could use the prospect of an attack with tactical nuclear weapons to deter South Korean responses to its provocations. The putative benefit of South Korean nuclear weapons against this threat is deterrence stability, causing North Korea to cease provocations and threats because its destruction would be assured. Contrary to this idea, however, it is more likely that South Korean nuclear weapons, rather than establishing deterrence stability, would instead further fuel an arms race and crisis instability.

South Korea already enjoys one of the largest, most technologically advanced militaries in the world, to say nothing of its alliance with the world’s strongest military power. But the basic security problem on the Korean Peninsula is not about the balance of capability between North and South, but the asymmetry of risk acceptance, the relative stakes in a conflict and the credibility of military responses as a result. Kim Jong Un is more risk acceptant than any South Korean leader could ever rationally be, both because he has more to lose from a conflict (war for him is a matter of literal survival) and because North Korea has a much smaller nuclear arsenal than that which the US could bring to bear on South Korea’s behalf. North Korea’s threats of nuclear escalation during a conflict are credible, whether or not South Korea possesses nuclear weapons. The balance of resolve will not shift in Seoul’s favor even if it transitions from a conventional defense posture to a nuclear-armed one.

Even though a South Korean nuclear capability is unlikely to materially strengthen deterrence of North Korea, it is becoming common to hear enthusiasm for an arms race in Seoul. The belief is that South Korea can bankrupt North Korea, forcing it to eventually capitulate just as the Soviet Union did to end the Cold War. But that is a highly caricatured depiction of how the Cold War ended that assumes Pyongyang would seek to match Seoul missile for missile rather than with asymmetric strategies. South Korea could outspend North Korea, but at what risks and costs? The US could finance the arms race against the former Soviet Union without courting bankruptcy or ruining civil society because the US dollar was the global reserve currency, and because it was buffered from direct conflict with the Soviets by two oceans and a network of alliances. The superpowers, moreover, were lucky on many occasions to narrowly avoid incidents that could have catalyzed nuclear war, such as during the Cuban Missile Crisis. Fears of surprise attack led to nuclear weapons placed on hair-trigger alert and policies to carry out a nuclear launch on warning to avoid an adversary’s disarming strike. The Cold War crisis instability could be even worse if replicated on the Korean Peninsula, given the even shorter decision-making timeframes and information asymmetries. Policymakers, and the South Korean public, should desire a more stabilizing approach to national security that doesn’t rely so heavily on luck for national survival.


If South Korea’s concern is that a future US president will precipitously withdraw from the South Korea-US alliance, or that the North Korean nuclear threat could lead to alliance decoupling, the hypothetical value of nuclear weapons is for insurance. Yet nuclear acquisition would fuel arguments in the US that could produce exactly those outcomes: a self-fulfilling prophecy of US retrenchment or a rupture in the alliance.

South Korea’s security is stronger so long as it remains partnered with the US. Similarly, Washington views alliances in Asia and Europe as a core pillar of its national security strategy. An independent South Korean nuclear capability would weaken the alliance’s foundations and undermine arguments for preserving it. Principally, if US policy elites come to view South Korea as a liability because of crisis instability and the risks of an attack on US territory that South Korean nuclear weapons would invite, they would be less willing to help shoulder Seoul’s security burden.

Some in South Korea may believe Washington needs Seoul and would ultimately choose to sustain the alliance despite South Korea acquiring nuclear weapons. To be sure, the Washington consensus on containing China through an Indo-Pacific security architecture might suggest that the US will bend over backward to keep its allies happy. But this masks change in the politics of US foreign policy. Few politicians state it so baldly, but former President Donald Trump’s views about the costs and risks of US commitments to South Korea and Japan as a reason he could accept both nations acquiring nuclear weapons is a dominant strain of thinking in today’s US Republican party. South Korean efforts to acquire nuclear weapons could be exactly the catalyst such Republicans would see as a reason to withdraw US troops and end the alliance. The Democratic party, meanwhile, would be unlikely to tolerate South Korean proliferation or shelter Seoul from the resulting global repercussions at the risk of eviscerating the global regimes that the US counts on to prevent its adversaries from acquiring nuclear weapons.


The need to deter future Chinese aggression is another rationale for nuclear weapons proffered by some advocates. Yet from the perspective of strategic alignment amid great-power rivalry, nuclear acquisition could actually invite stronger Chinese coercion, not deter it.

Even though South Korea is a staunch US ally, it has a tradition of playing geopolitics so as to preserve its strategic autonomy — especially over China. Taking care not to co-operate with China or the US in ways that alienate one or the other is what makes South Korea pivotal to regional security. In fact, alongside its significant GDP growth, robust defense capability, and exports of automobiles, electronics and nuclear reactors, another of South Korea’s sources of power is its ability to balance its interests in shifting geopolitical currents. This is a dance that has helped keep Seoul’s neighborhood from becoming even more of a powder keg and stopped South Korea becoming a more direct target of Chinese coercion.

The question for South Korean statecraft, then, is what effect nuclear acquisition would have on its ability to preserve this posture. With China’s growing power and more active military activity to protect its interests in the region, Seoul is confronted with difficult choices: become a Chinese vassal or band with the US and others to deter Chinese aggression, choices that both fuel rather than ameliorate great-power rivalry. The middle path is to encourage restraint and compromise on all sides. Given how coupled South Korea’s economy is to China, Seoul seems likely to continue aiming for this: not antagonizing China by overtly siding with the US in an outright containment strategy, but keeping Washington engaged without becoming entangled in its broader regional objectives, perceived in Beijing as anti-China.

Nuclear weapons would make this balance far harder to achieve. As well as the potential to lose US support, as discussed above, nuclear weapons will undoubtedly cause China to see South Korea as a more prominent threat. Rather than buffering the prospect of Chinese aggression, nuclear acquisition could provoke Chinese responses that heighten regional rivalry dynamics (including through greater support of North Korea) and degrade South Korean economic and military security. Seoul might argue that its nuclear deterrence is directed at Pyongyang, but with missiles capable of striking targets in China, Beijing is unlikely to find this convincing. China’s response to the THAAD deployment — which involved diplomatic condemnation of South Korea and an extended period of economic screw-turning as punishment — is indicative of how Beijing interprets ostensibly North Korea-specific capabilities that nevertheless are perceived to impact China.


South Korea’s threats are more manageable than solvable. North Korea will have nuclear weapons for the foreseeable future; fears of abandonment are a structural element of alliances, including those with the US; and China will always be larger and stronger. Nuclear weapons resolve none of these problems and make managing all of them much harder. Indeed, South Koreans would likely find nuclear weapons a poor substitute for a robust military alliance with a solid track record of deterring war with North Korea. And South Korea would not want to have to deter aggression by both North Korea and China, conceivably without US support.

Arguably South Korea’s best “threat management” path is the one with a proven track record. Principled and careful diplomacy with North Korea on steps to avoid triggering conflict reduces the prospect of nuclear attack. Sustaining the US alliance, and where possible deepening trilateral co-operation with Japan, will continue to be Seoul’s best form of security for deterring North Korean coercion, imperfect as it is. And engaging China with an eye to both avoid becoming Beijing’s enemy and encourage a less intense competitive rivalry between Asia’s modern-day great powers maximizes South Korea’s sovereignty. The shrimp is safest when the whales don’t fight.

This strategy may not have popular appeal, but it would be cheaper, more effective and less risky than nuclear acquisition

Image: DEMA(Defense Media Agency) Official Photographer: lee kyung won

Related Articles