The Peninsula

An Insider’s View on South Korea’s Nuclear Armament Debate

North Korea has continued to multiply its nuclear threats and strongly expressed its resolve to preemptively strike South Korea and the United States with nuclear weapons in the event of a crisis. In 2021, the North Korean regime developed tactical nuclear weapons targeting the Korean Peninsula and surrounding areas. It also documented conditions in which they would use nuclear weapons in a new law on nuclear policy in September 2022. Recent developments have raised concerns among South Korean officials and experts regarding the difficulty in deterring North Korea’s nuclear threats with U.S. extended deterrence.

Under direct threats of what North Korea itself calls “‘overwhelming nuclear force,” South Korea has more than enough security motives for its own nuclear armament than ever before. But if South Korea should take on a nuclear armament at the expense of the currently provided U.S. extended deterrence, the answer to whether it is really the right policy choice could be quite different.

Three Loopholes in Pro-Armament Argument

Proponents for self-nuclear arming have been strongly motivated by public opinion. In a recent survey conducted from Nov. 28 to Dec. 16, 2022, 76.6 percent replied that South Korea needs to develop nuclear weapons independently to counter Pyongyang’s intensifying nuclear threats and deter its provocations. But according to a research paper, such high public approval rating may be in fact the result of insufficient awareness of the potential impact of a nuclear armament.

A paper published in 2020 sought to answer whether such public opinion poll results actually meant that South Korean voters really desired their own nuclear armaments. Researchers forced a group of respondents into an experimental set-up in which respondents were exposed to expert information conflicting with their predispositions on nuclear armament. The results of this experiment show that when respondents are given expert information, the proportion of the pro-armament group decreased from 61 percent to 38 percent. The findings of the study show that opinion surveys have a serious limitation in revealing voters’ true preferences on a sensitive and complex issue such as nuclear armament. Indeed, experts’ opinions are quite different from those of public. According to a survey of 50 South Korean diplomatic and security experts conducted by a Korean newspaper on February 23, 2016, 64 percent of them opposed South Korea’s nuclear armament. In a 2022 survey by the Korean Institute for National Unification, 45 out of 67 security experts, or 67 percent expressed negative views on whether South Korea should arm itself.

Second, those in favor of nuclear armament believe that the U.S. is not likely to trade its national interest for its security guarantee to Seoul at a critical moment. Such decoupling would only happen if Pyongyang decided to use nuclear weapons on the Korean peninsula, and Washington decided not to strike back. However, North Korea’s actions depend on their expectation of the United States’ reaction, and they can never be confident that the U.S. would not retaliate. Indeed, deterring adversaries is much easier than assuring allies. The U.S. might not assure South Korea even with 95% credibility about its willingness to retaliate in case of North Korea’s nuclear use on the peninsula. However, Kim Jong-un would never hit his nuclear button even if there is only a 5% possibility of a U.S. counter strike to Pyongyang. This is the case in which North Korea is yet to have a second-strike capability against the United States.

If North Korea uses nuclear weapons despite the U.S. commitment to South Korea, it would represent a major failure of the U.S. policy of extended deterrence. Then the world, including 30 allies relying on U.S. extended deterrence, would watch how the U.S. reacts. If the U.S. does not fight back through fear of North Korea – which has incomparably limited nuclear weapons than the United States – its global leadership and alliance network will collapse immediately. Therefore, the U.S. should use every possible means to prevent North Korea from ever using their nuclear weapons first and it is definitely in the U.S.’s vital interests.

The last loophole is that proponents for nuclear armament relies on the assumption that our own nuclear weapons may have more of a deterrence effect on North Korea than the U.S. extended deterrence does. Would North Korea believe that South Korea can make a quicker decision to use nuclear weapons than the United States? If we compare the two options, the U.S. extended deterrence is more credible in terms of its capabilities than South Korea’s own potential nukes. On the other hand, South Korea’s own potential nuclear armament would be arguably more credible in terms of its intention or resolve, that is, that we can retaliate with nuclear weapons at our will should we ever be attacked by North Korea. If South Korea cannot show its resolve to increase its chances of use even with its own nuclear arsenal, self-nuclear armament can never be a better option than the U.S. extended deterrence. On the narrow Korean Peninsula, South Korea’s use of nuclear weapons against the North is only possible if it risks destroying itself, too.

Three Reasons to Keep the Option on the Table

Nevertheless, it is not desirable to completely rule out nuclear armament as an option to consider in the future where situations may develop that may reverse all of this logical thinking. South Korean President Yoon’s recent remarks are probably based on these ifs. First of all, there is a situation in which the possibility of Pyongyang’s misperception and miscalculation will increase. The second is when an irrational leader like Donald Trump gains power again in the United States. The last is when the U.S.-China strategic competition intensifies in a direction that is not friendly to the United States.

Even though the United States is confident of its extended deterrence against North Korea, Kim Jong-un may miscalculate the North’s chances of winning. Deterrence logic is based on a rational actor perspective, but North Korean leadership may become vulnerable to staying rational or their rationality might be constituted of very different calculations. As Pyongyang has developed tactical nuclear weapons and lowered the threshold of nuclear exchanges, the risk that a non-nuclear conflict can escalate into a nuclear war is increasing. If North Korea perceives itself at a disadvantage, it is more likely to use its nuclear weapons first with “the fear of being a poor second for not going first.” South Korea can never rule out this strategic risk but it is understandable that with pacing challenges from China and an acute threat from Russia, the United States has less concern of North Korea than its ally.

Second, even the U.S. security establishment, which values the ROK-U.S. alliance, may not rule out a situation in which an element in the U.S. domestic politics, especially the leadership, could decrease U.S. commitment to South Korea. South Korea experienced this during the former Trump administration and realized that the U.S. could make a concession in its military relations with South Korea without prior consultation with South Korea. With a deadlocked security environment on the peninsula, China’s increasing influence in the Indo-Pacific region, the U.S. administration may make a compromise to what they think best with North Korea, if not desirable for South Korea. If a president or a majority of U.S. tax payers is fed up with the need to protect the rule-based order, its global leadership, and a huge alliance network, it does not make any sense that South Korea should then adhere to non-proliferation and extended deterrence at the expense of its survival.

The third possibility is a more long-term approach. In a scenario in which U.S.-China competition intensifies, and China tries to dominate at least the Indo-Pacific region, the U.S. should inevitably ease its adherence to the current rule-based order to win against China. If the U.S. concludes that it is necessary to have a nuclear ally in the region to prevent threats from China, or threats from strategic cooperation among the region’s three nuclear armed states (North Korea, China, and Russia). In this case, a narrow window can be open for South Korea’s nuclear armament that the United States may accept, as the United States lifted missile limits on South Korea in 2021. However, South Korea will be able to maintain its strong alliance with the United States and avoid international criticism and sanctions only when such nuclear South Korea strongly solidifies its relationship with the U.S. and confronts their common threats.

No one can rule out those ifs, especially in military dynamics. The ROK-U.S. alliance should prepare for them and develop a better policy option that can address both parties’ priorities and concerns. With a tailored deterrence strategy (TDS) currently under revision, they should make substantive progress for joint nuclear planning that encompass sharing scenarios and exchanging operational considerations, and that explores more precise and flexible options according to North Korea’s varied nuclear threats – from tactical to strategic.

Kyung-joo Jeon is a Research Fellow at the Korea Institute for Defense Analyses. Her areas of interest in research include North Korea’s military or political issues and South Korea’s defense planning. The views expressed here are the author’s alone.

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