The Case for a Nuclear South Korea

President Yoon Suk Yeol pays respect to the late president Park Chung-hee, who attempted to build a nuclear weapon during the 1970s but was thwarted by American intervention. Office of the President of the Republic of Korea

For the first time, a South Korean president officially mentioned the possibility of his country going nuclear. Although Seoul quickly retracted and reaffirmed its commitment to the Non-Proliferation Treaty (NPT), President Yoon Suk Yeol’s remarks fueled debate about whether South Korea—a major American ally that hosts 28,500 American troops—should seek nuclear weapons to defend against North Korea, a de-facto nuclear-armed state. Not surprisingly, the responses from the Beltway were negative. Ankit Panda, the author of Kim Jong Un and the Bomb, argued that nuclear weapons will not solve South Korea’s security problem. Siegfried Hecker, former Director of Los Alamos National Laboratory, who traveled to North Korea multiple times, pointed out that such a move would undermine South Korea’s largely successful civilian nuclear industry and soft power, thereby “shooting itself in the foot.” Nonetheless, this article argues that the United States should not easily discard a nuclear option for South Korea. Endorsing Seoul’s nuclear path tacitly, Washington may be able to ensure regional stability with the help of South Korea.

Why Does South Korea Seek a Nuclear Weapon?

The gravity of the security threat South Korea faces today is dire. After detonating its first nuclear device in 2006, North Korea conducted six nuclear tests and hundreds of ballistic missile tests; these missiles can reach Seoul, Tokyo, Guam, San Francisco, and New York. According to a RAND study, Pyongyang’s nearly 6,000 artillery systems could kill thousands of South Koreans “in just an hour, even without resorting to chemical or nuclear weapons.” The regime also possesses the world’s fourth-largest military with more than 1.2 million personnel and a range of asymmetric capabilities that includes cyber warfare, drones, and counter-space capabilities. However, Pyongyang’s rising nuclear ambitions dwarf these conventional threats. Even Ankit Panda has noted that Kim Jong Un has overseen “a massive project of quantitative nuclear force expansion and qualitative modernization,” with no end in sight.

Countering the North’s mounting threats, the South has sought to double down on furthering its conventional military capabilities and on hardening the so-called nuclear umbrella provided by the United States. Under these extended deterrence arrangements, Washington assures that any armed attack—either nuclear or conventional—on South Korea will result in a forceful retaliation—nuclear or conventional—from Pyongyang. However, Thomas C. Schelling and other scholars warned of the inherent credibility problem in extended deterrence, in which there is a dissociation between a party who bears the costs of deterrence and a beneficiary of deterrence. It is important to note that all nine major wars since the 19^th century, including the Korean War but except the Franco-Prussian War, broke out due to the failure of extended deterrence. For instance, the British failed to deter Germany from attacking Belgium, its treaty ally, during World War I. Now, as North Korea can target American cities, it is ever more questionable whether US policymakers are willing to risk San Francisco for Seoul were extended deterrence to fail. During the Cold War, this phenomenon of “decoupling” prompted French president Charles de Gaulle to ask John F. Kennedy if he would sacrifice “New York for Paris,” a question that ultimately led France to establish its independent nuclear program.

To resolve this credibility problem in extended deterrence, Schelling and other experts suggested deploying tripwire forces to allied territory. United States Forces in Korea (USFK) has acted as this tripwire since the end of the Korean War and contributed to the stability of the Korean Peninsula. However, this arrangement has been thoroughly discredited.

First, North Korea has already bypassed the tripwire and has directly targeted South Korea. In the 1960s and 1970s, the North even targeted Americans—the axe murder incident and the capture of USS Pueblo are good examples. But, recently, the North Korean military has more brazenly circumvented the tripwire without incurring costs. The sinking of the Cheonan, the shelling of Yeonpyeong Island, and the 2015 landmine crisis inflicted heavy casualties on South Korea, but not on the United States. During these provocations, the United States was reluctant to intervene forcefully and instead tried to restrain the South from retaliating against the North for fear of escalation. Although these incidents did not involve nuclear weapons or large conventional forces, the U.S. failure to deter or punish Pyongyang discredited extended deterrence. In short, as Van Jackson puts it, the United States was failing to respond to “small raindrops,” and South Korea started to cast doubts on the reliability of the overall extended deterrence umbrella that the United States promised to provide.

Second, Seoul’s fear of abandonment has been ever-increasing since the middle of the last century. It is noteworthy to mention that the withdrawal of U.S. forces from the peninsula in 1949 was one of many contributing factors to the outbreak of the war that almost wiped out South Korea from the map. Even after the war, four U.S. presidents considered withdrawing soldiers from the peninsula and two other administrations reduced troop numbers according to changes in the U.S. global posture. The Nixon Doctrine of 1968, articulating that Asian security problems should be handled by Asian nations, and the Carter Administration’s threat of complete withdrawal from the peninsula deeply traumatized Seoul. It was to hedge against such American retrenchment that South Korean President Park Chung-hee pursued covert nuclear and missile programs in the 1970s. Most recently, the Trump administration again considered pulling out all US troops from South Korea. The United States has withdrawn its military support from allies before, most notably in South Vietnam and recently in Afghanistan—it is however important to point out that, unlike the U.S.-South Korean alliance, the United States did not have treaty obligations or long-standing alliance structures with these countries. Thus, even though the tripwires are present in the country and the U.S. security commitment to its ally is “rock-solid”, the recurring pattern of American retrenchment haunts South Korea and drives its insecurity. It is worth asking what the current U.S. strategy for combating the North’s nuclear expansion is. It has not had a workable solution for decades.

In short, the reason why South Korea wants a nuclear option is straightforward. The country faces a clear existential threat from a nuclear-armed North as its reliance on U.S. extended deterrence is waning. Some argue that North Korea’s quest for a nuclear arsenal as a way of guaranteeing its security from the United States is rational. Considering this, however, it would also be rational for South Korea to go nuclear.

Why Is a Nuclear South Korea Good for America?

A nuclear South Korea can serve American interests. First, it will provide Washington with much-wanted leverage over denuclearization negotiations with North Korea and its backers. For the past 30 years, the North has manufactured nuclear crisis after nuclear crisis. Since 1994, the United States with its allies attempted all diplomatic means—bilateral, multilateral, top-down, and bottom-up—to denuclearize North Korea, but failed to halt its nuclear proliferation. To dissuade the North from continuing its nuclear ambitions, China and Russia, the regime’s backers, need to be on board with the rest of the international community. However, it seems that the two regional powers are content with the status quo; they prioritize their geopolitical interests—namely maintaining stability and limiting American influence in the region—over the denuclearization of North Korea. The two countries were reluctant to enforce U.N. sanctions on North Korea and recently wielded a veto on a U.S.-proposed resolution for tightening sanctions on North Korea at the U.N. Security Council. Keeping all options available, including arming South Korea with nuclear weapons or redeploying “tactical” nuclear assets to South Korea to counter the North, will raise the stakes and change Beijing and Moscow’s calculus. They will be vehemently against the idea, but that is exactly the point.

There would be a short window for China or Russia to pressure the North to restrain its nuclear program. A nuclear-armed South Korea, possibly followed by Japan, will be the last thing the two countries would want: it is against the two countries’ core interests in maintaining regional stability. Beijing will undoubtedly retaliate against Seoul’s nuclearization through economic coercion as it did when the latter decided to host the U.S. Terminal High Altitude Area Defense (THAAD) missile systems in 2017. But there are limits to China’s economic leverage over South Korea. Also, it is important to note that these two countries acted before: they signed the toughest sanctions that cut off the North’s most lucrative exports and oil imports in 2017 when President Trump’s threat of “bloody nose strikes” seriously endangered regional peace and security.

Second, a nuclear South Korea also can serve U.S. security interests in the long run. Nuclear proliferation in East Asia can promote regional stability and lessen the U.S. burden of defending its allies against the mounting threats from North Korea, China, and Russia. In this regard, a Seoul-based analyst asserted that the United States will actually “become safer” and “the alliance will never be put to a test.” North Korea will be less likely to use its nuclear weapons against a nuclear-armed South because direct deterrence is more compelling. Furthermore, John Mearsheimer argued that nuclear weapons “bolster peace by moving power relations among states toward equality.” In light of Russia’s invasion of Ukraine and threat to use nuclear weapons, it is worth rereading his foresighted argument for a nuclear-armed Ukraine back in 1993:

A nuclear Ukraine makes sense… it is imperative to maintain peace between Russia and Ukraine. That means ensuring that the Russians, who have a history of bad relations with Ukraine, do not move to reconquer it. Ukraine cannot defend itself against a nuclear-armed Russia with conventional weapons, and no state, including the United States, is going to extend to it a meaningful security guarantee. Ukrainian nuclear weapons are the only reliable deterrent to Russian aggression. If the U.S. aim is to enhance stability in Europe, the case against a nuclear-armed Ukraine is unpersuasive.

Like the Russia-Ukraine relationship, South Korea shares a troubled history with China. China believes that the Korean Peninsula belongs to its sphere of influence as Russia does with Ukraine. As such, US policymakers should consider how a nuclear-armed South Korea can be instrumental in balancing China in the near future. As India provides a counterweight to China in South Asia, South Korea can play a pivotal role in checking China’s expansion in East Asia.

In conclusion, the case for a nuclear-armed South Korea is strong. Washington should not easily dismiss this possibility, as it can provide diplomatic leverage vis-à-vis Beijing and Moscow in its efforts to denuclearize North Korea. Moreover, a more capable ally will also help the United States save strained military resources and focus more on its strategic competition with China. Undoubtedly, South Korea’s adoption of nuclear weapons will seriously challenge the non-proliferation regime. However, one should remember that South Korea is not the first country to buck it; no international regime that defies the national interest is sacred. The NPT was established as a means to maintain international order and not as an end in itself. Shocked by the Russian invasion of Ukraine, Abe Shinzo, the late Japanese prime minister, and other political leaders in Japan discussed the possibility of going nuclear for Japan’s self-defense. Some American experts advocate for a nuclear Taiwan to defend the island against a Chinese takeover. In this regard, a nuclear South Korea is not a wild idea, and it can be a viable solution for restoring and maintaining regional stability.