The WMD Project is an ongoing endeavour by the APLN’s network of experts to assess regional security issues, proliferation challenges, and flash points in the Asia-Pacific.

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This special report by Professor Chung-in Moon analyses the prospects of South Korea and Japan seeking independent nuclear forces in light of the DPRK’s growing nuclear and missile threats.

There are ongoing fears that the unresolved DPRK nuclear issue may trigger a nuclear domino effect in Northeast Asia, driving Japan and South Korea to go nuclear. Both Japan and South Korea have an enormous latency to turn their civilian nuclear programs into nuclear armament. They possess both fissile materials that can be enhanced to weapons-grade and the technological capabilities to do so.

These concerns are heightened following the recent news of the IAEA reporting plutonium reprocessing activity at DPRK’s Yongbyon nuclear power plant and DPRK’s claim that it successfully tested a new hypersonic missile called Hwasong-8.

Professor Moon recommends that to prevent nuclear conflict and improve the overall security environment in Northeast Asia it is important to address the DPRK nuclear quagmire peacefully, slow down the strategic arms race between the United States and China, and improve South Korea-Japan bilateral relations.

In the report, he traces the growing nuclear and missile capabilities of the DPRK, and how these developments have shaped political and public debates on nuclear weapons in the ROK and Japan. He examines and dismisses the various arguments mustered by pro-nuclear camps in each country, and notes the urgency in reinforcing the reluctance by officials to entertain nuclear armament by increasing civil society education and mobilization.

He concludes that the DPRK’s nuclear and missile threats have greatly heightened the potential for a nuclear domino effect in Northeast Asia by increasing the temptation for the acquisition and development of nuclear capabilities in South Korea and Japan for defensive and security reasons. However, this nuclear domino effect exists as a possibility, but not a concrete reality.

The key highlights include:

• Since 2002, the DPRK has made steady progress in its nuclear weapons capability. While it now has nuclear facilities, fissile materials (both plutonium and highly enriched uranium), and a stockpile of about 30 to 60 warheads, mix of new strategic and tactical weapons, it is estimated that the DPRK can increase its nuclear arsenal by six to twelve warheads per year. Pyongyang’s intention seems to not only gain a second strike capability targeted at the U.S. mainland, but also to acquire tactical deterrence by denial against South Korean forces, American forces in Japan and South Korea, and U.S. reinforcement forces.
• With the DPRK’s growing nuclear and missile threats in the recent years, conservative leaders in both ROK and Japan have reactivated old public debates about nuclear rearmament in recent years. The unpredictable nature of American security commitment, China’s rise and the deepening of strategic instability in Northeast Asia have also fuelled these domestic debates.
• In the ROK, one school of thought – the teleological school – seeks nuclear armament regardless of American stance. It promotes ‘nuclear sovereignty’ based on the logic of ‘nuclear for nuclear.’ The other school of thought – instrumentalist, which has an upper hand – pushes for a conditional, independent nuclear armament based on enhancing the credibility of US nuclear extended deterrence. They favour redeployment of American tactical nuclear weapons or nuclear sharing between the ROK and the United States. A sudden rise in Pyongyang’s assertive behaviour can bring back pro-nuclear sentiment in South Korea’s public opinion.
• Japanese conservatives too have resuscitated old Japanese debates about an independent nuclear force with a view primarily to using Japan’s nuclear weapons latency as a political weapon in relations with an ever-more assertive China.
• However, the nuclear domino is not likely to materialize anytime soon in Northeast Asia. This is because, both the Japanese and South Korean governments are fully committed to their non-nuclear stance and have resisted being drawn into loose talk of nuclear weapons proliferation. They have observed stringent monitoring and verification of their nuclear materials facilities and stocks of fissile material. They also lend full confidence in American extended nuclear deterrence and, therefore, oppose the redeployment of tactical nuclear weapons and the NATO-type nuclear sharing.
• While both countries have the necessary missile delivery technology available, neither is likely be a breakout nuclear state. Fear of international sanctions and negative impacts on their economy and the civilian atomic industry, a potential rupture in their alliance relationship with the United States, and a dangerous nuclear arms race on the Korean peninsula are likely to be an effective deterrent against the nuclear move.
• Japan’s peace constitution, three non-nuclear principles, and Japan’s excessive reliance on American security protection are also likely to prevent Japan’s move toward nuclear armament. In contrast to ROK, public opinion in Japan is opposed to nuclear armament and the nuclear taboo is deeply rooted in Japanese society. Civil society groups in the ROK and Japan are forming countervailing coalitions opposed to nuclear armament.

Recommendations include:

• Mitigating the overall security environment in Northeast Asia is critical for preventing a nuclear domino in this region. The DPRK nuclear quagmire should be resolved peacefully, and China’s nuclear modernization and build-up should also be addressed.
• Improvement of Japan-South Korean relations can prevent a nuclear domino, as protracted antagonistic confrontation between the two countries becomes a breeding ground for a nuclear arms race.
• The US can play a more constructive role in reshaping the nuclear equation in the region by signalling and assuring adequate extended deterrence, while avoiding the tolerant attitude of nuclear venture in Japan and South Korea, and by slowing down the strategic arms race in the region.
• Transnational coalitions between hardliners on nuclear weapons development in the DPRK, South Korea, and Japan should be rejected. Civil society and NGOs in Japan and South Korea should cultivate solidarity and work toward anti-nuke movements.
• National and international efforts to educate citizens on the danger of nuclear weapons by disseminating timely and objective information is important.

About the Author

Dr Moon Chung-in is the chair of the Sejong Institute and vice chair of the Asia-Pacific Leadership Network for Nuclear Non-proliferation and Disarmament. He is the former special adviser for Unification, Foreign and Security Affairs to the ROK President. Dr Moon is currently the editor-inchief of Global Asia, a global issues quarterly journal published in English. He currently holds a variety of academic titles, including distinguished university professor at Yonsei University, Krause Distinguished Fellow at the School of Global Policy and Strategy of the University of California at San Diego (UCSD), a distinguished professor of the ROK National Defense University. Dr Moon has also served as the executive director of the Kim Dae-Jung Presidential Library and Museum and as the chair of the Presidential Committee for the Northeast Asian Cooperative Initiative of the Roh Moo-hyun government, a cabinet-level post. He was also an ambassador for International Security for the ROK Ministry of Foreign Affairs and Trade, and he attended the first (2000), second (2007), and third (2018) Korean summits in Pyongyang as a special delegate. He has held positions as the vice president of International Studies Association of North America (ISA) and the president of Korea Peace Research Association. Dr Moon has authored, co-authored, and edited 60 book, and published over 300 articles in academic journals including World Politics, International Studies Quarterly, and World Development.

This paper was presented to the APLN Weapons of Mass Destruction (WMD) in the Asia-Pacific Workshop, December 1-4, 2020, and is part of an upcoming edited volume from experts in the region titled “WMD in Asia Pacific: Trends and Prospects,” which is scheduled to be published later in 2021. The workshop was funded by the Asia Research Fund (Seoul).

Disclaimer: The views expressed in this report do not necessarily reflect the position of the Asia Pacific Leadership Network or any of its members.

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