What South Korea Needs for Nuclearization

Abstract

Since the former President Yoon Suk Yeol mentioned about self-nuclearization in 2023, the nuclear debate of South Korea has evolved into an actual policy discourse from hypothetical academic topic. Although the debate has went underground due to the martial law incident in 2024 and the start of a new government in 2025, it is still one of the heated topics among the experts in defense and security areas. This article will analyze the logics of both sides that support and oppose nuclear development of South Korea, observe South Koreans’ view on international security and nuclear, point out what they are missing in the pathway toward nuclearization, and see what South Korea needs for actual nuclear armament.

Introduction

On May 9, 2025, France and Poland signed a treaty on enhanced defense cooperation, including nuclear energy.[1] Since 2020, President Emmanuel Macron has expressed his willingness to improve France’s role in European security through its nuclear capability, known as the ‘French offer’,[2] and he also addressed that he is open to extend French nuclear protection in March 2025, as President Donald Trump kept questioning the integrity of NATO amid the Ukrainian War.[3]

And on June 21, President Trump announced that the U.S. aircraft had struck three major nuclear sites in Iran.[4] This active intervention to Israel-Iran War might be seen as U.S. show of power, but many concerned it would only escalate the tension in the Middle East, which will give more reasons for Iran to engage in its nuclear program.

South Korea has been familiar with the word ‘nuclear’ thanks to its neighbor up north, but the perception of this term is slowly changing. The nuclear armament issue went up to its peak in 2024, as the tensions around the Korean Peninsula and upcoming U.S. presidential election by then added more unpredictability. The nuclear debate in South Korea seems to have gone away for now as former President Yoon Suk Yeol was impeached and liberal government came to power. However, the ongoing situations in Ukraine and Middle East show that South Korea should consider standing on its own, as the U.S. cannot be omnipresent in terms of security, and the debate on nuclearization will return – at some point.

Nuclear Debate in South Korea

South Korea’s nuclear armament is not a new topic, but it had been rather a hypothetical discourse than a realistic policy assessment. This convention was broken in January 2023, as former President Yoon said, for the first time as the President, that South Korea could build its own nuclear weapons if North Korean threat continues.[5] And despite Yoon’s efforts to strengthen security ties through Washington Declaration, emphasizing ROK-U.S. extended deterrence, The Spirit of Camp David, strengthening ROK-U.S.-Japan trilateral cooperation, and several other defense treaties with like-minded partners, the idea of nuclearization remained in public to some extent. In 2024, a survey showed that over 70 percent of the public supports South Korea’s nuclear weapon development,[6] unlike what majority of Korean experts think.[7]

For those who support nuclear armament, North Korea is always at the core of their reasons. Their main arguments are: Kim Jong Un continues to develop nuclear capabilities and South Korea cannot depend on the U.S. forever; the U.S. will not be able to help South Korea if distractions from Ukraine and the Middle East continue; and U.S. commitment toward South Korea might not be as strong as it used to be under Trump. Ultimately, a combination of imminent threat, vulnerability and distrust is an underlying sentiment of the South Korean public.

There are some foreign arguments that South Korea should go nuclear as well.[8] Robert Kelly, professor at Pusan National University, argued that South Korea should have its own deterrence against North Korea’s rising nuclear capabilities, and South Korea has a legitimate reason to withdraw from the Treaty on the Non-Proliferation of Nuclear Weapons (NPT);[9] and Andrew Yeo, senior fellow of Brookings Institution, claimed that Trump might allow South Korea to have its own nuclear weapons, in hopes of strengthening its deterrence against North Korea and relieving public anxiety in South Korea.[10]

While supporters mainly concern about risks and threats of the present, the opponents mainly worry about the collateral damage in the future, which cannot be precisely predicted in the world of international security. Their basic standpoint is that South Korea is one of the core members of rules-based international order, and nuclear armament with withdrawal from NPT will put South Korea’s international status and reputation at stake.

Unlike the view of supporters that nuclearization could be an answer to North Korean threat, the opponents argue that it will only intimidate North Korea; and in worse case, China and Russia could also perceive South Korea as another rising threat. Moreover, many East Asian experts worry South Korea’s nuclearization could cause a domino effect, encouraging Japan and other countries around the region to develop their own nuclear weapons.[11] Of course, the security environment in the Indo-Pacific region is different from that in Europe: as NATO is a multilateral alliance with nuclear sharing structure, whereas the Indo-Pacific basically upholds hub and spoke system, granting majority of its authority (half in theory) to the United States. No U.S. ally in Asia has nuclear weapons, and the U.S. has preferred to keep such asymmetric alliances. But as the security anxiety grows within the region, the nuclear debate in South Korea will grow, and the possibility of South Korea becoming the first domino remains.[12]

South Korean Views on Northeast Asian Security

South Korea has three realistic options in this nuclear debate: the first would be maintaining status quo, depending on U.S. nuclear umbrella along with other Indo-Pacific partners; the second option is nuclear sharing, which is to deploy U.S. nuclear weapons in the South Korean territory; the third option is to prepare for its nuclear capability in case of war or any equivalent level of crisis via acquiring nuclear latency. Among these three options, there are inherent reasons why South Korean public is highly against the first, and more in favor of the third.

First, there is a strong distrust in the effectiveness of enhanced deterrence (Washington Declaration) and trilateral cooperation (Camp David Summit). South Korean politics today is extremely polarized, and it seems highly unlikely that the new government would continue former impeached government’s foreign policy. If Yoon had stayed in power, South Korea could have led both bilateral and trilateral cooperations as both leaders in the U.S. and Japan were about to change. And now, where all three leaders have not inherited the legacy by tossing the baton to one another, and under the new government that had criticized Yoon, including his diplomatic endeavors, the future of South Korea’s bilateral and trilateral relations is unclear.

Second, South Korea’s interest in foreign affairs is highly asymmetric; in other words, they focus on North Korea too much, while they care too less about other global issues. This could be a serious problem, as the demand of the public is expressed through elections in democracy, and it might trump the voice of rationality. This could lead to an unexpected development: if South Korea remains hesitant to global engagement (i.e. Ukraine, Taiwan, the Philippines, etc.), the U.S. could lose its interest in protecting South Korea even more; and this chain reaction could meet a tragic result in South Korean security.

Such omen did happen in 2024. As the U.S. commitment toward South Korea has been distracted due to tensions in Taiwan Strait and South China Sea, the Yoon government and the ruling conservative party began to raise nuclear armament issue. Despite the South Korean conservatives tend to have a strong faith in ROK-US alliance, they were anxious of facing North Korea’s rising threat, while neglecting the serious issues that the neighbors down south are going through. The same pattern is being observed nowadays, as Trump’s interest is shifting from North Korea via Russia to Iran. If South Korea’s trust toward the U.S. continues to fall, along with the ongoing tariff issue, the nuclear debate will soon rise again as a survival strategy.

Third, there is a perception gap between maintaining international status and possessing nuclear weapons. It seems like the South Korean public pictures their nuclearized status similar to that of the United Kingdom or France, not India or Pakistan. Ever since the NPT came in effect in 1970, every country that attempted to develop nuclear weapons has gone through a severe international pressure, with sanctions and political condemnations, regardless of its success. Until today, the Permanent Five members of the UN Security Council are the only legitimate nuclear states under the NPT, and North Korea is under international criticism for its withdrawal from the treaty and nuclearization.

If South Korea wishes to secure its nuclear latency without withdrawing from the NPT, strong support from an overwhelming majority of NPT signatories, including the U.S., UK and France, will be needed. Though it is obvious that China and Russia will strongly oppose South Korea’s nuclear development, other NPT members might also be suspicious of, if not against, South Korea’s nuclear capabilities. Therefore, along with the effort to overcome institutional limitations of non-proliferation by revising the ‘ROK-U.S. Agreement for Peaceful Nuclear Cooperation (known as the 123 Agreement)’,[13] South Korea needs diplomatic capabilities to win global trust and support by emphasizing its commitment and responsibility as a country protecting world’s liberal order.

Conclusion

South Korea itself is a recipient of international support, as it survived the Korean War thanks to the UN Forces. The more South Korea gets carried away with North Korea and fixates its interest only within the Korean Peninsula, the less support it would get from the international community. Ironically, South Korea should take a step back from North Korea and take more steps toward the ongoing security issues in various regions to address the North Korean issue more effectively.

South Koreans must realize that nuclear means more than what they think in the arena of defense and security. If South Korea’s will for nuclearization continues, it should earn a firm global trust and support through a long-term commitment to international security. Also, South Korea as a state, not as an individual administration, must come up with a concrete plan to prevent any potential side effects, such as domino effect, nuclear race, and unexpected military conflicts. Afterall, with great power comes great responsibility