Nuclear Security in a Changing East Asian Landscape: South Korea and Japan’s Complex Dilemma

The contemporary International security environment amid the Ukraine war has created discomfort among United States allies in the Indo-Pacific. China’s military buildup, North Korea and Russia’s mounting provocations have created a tense regional environment for South Korea and Japan. South Korea and Japan have been under the US Nuclear security umbrella for years now, but the regional security situation has put both states in a nuclear dilemma.

The discourse on nuclear security has gained popularity since the onset of Ukraine war, and the nuclear developments of North Korea are a primary concern for South Korea. Domestic opinion has been changing in Seoul and the President Yoon Suk Yeol has echoed it. During a policy briefing session in January, he stated that South Korea could contemplate the possibility of developing its own nuclear weapons in response to a further escalation of the nuclear threat posed by its northern neighbour. He further added that his country can also ask the United States to redeploy tactical nuclear weapons on the Korean peninsula, but subsequently clarified that the comments did not depict a policy change at the official level but rather a representation of changing public opinion. This was the first time that a South Korean President spoke about acquiring nuclear weapons since the 1990s, when the US removed its tactical nuclear weapons from the region. According to a survey conducted in February 2022 by the Chicago Council on Global Affairs and the Carnegie Endowment for International Peace, 71% of respondents from South Korea expressed their endorsement for the pursuit of nuclear weapon development by their nation, while 56% indicated a preference for the reintroduction of US tactical nuclear weapons to the peninsula.

The shift in public opinion is due to the increasing distrust of the public towards US extended deterrence as the US commitment to South Korean security depends on American leadership. Former US President, Donald Trump in 2016 called South Korea a free rider and threatened to withdraw US troops stationed in South Korea if Seoul does not cover its costs. The fears still exist in public which believes that American promises are only dependent on it leadership and that if any leader like Donald Trump comes into power once again, Seoul’s security will be compromised again. Seoul Mayor Oh Se Hoon also supported the idea of South Korea’s nuclearization in an interview conducted in March this year. South Korea’s ambitions of developing nuclear weapons are not new. In the 1970s, it carried out a secret program to develop them but had to give up soon due to increased pressure by the United States. South Korea chose to come under the US security umbrella and thousands of US troops are still stationed in the region.

Japan, being a previous victim of nuclear cruelty and currently surrounded by a nuclear-armed neighborhood, also faces a security dilemma. Japan has been a proponent of peace and global disarmament all these years. In 1967, the Three Non-Nuclear Principles were introduced by then-Prime Minister Eisaku Sato which define Japan’s nuclear policy to date. The principles included Japan’s commitment to refrain from owning, producing, or introducing nuclear arms. Japan further solidified its stance by ratifying the Non-Proliferation Treaty (NPT) in 1976 and the Comprehensive Nuclear Test Ban Treaty in 1997. Over the years, Japan has maintained its dedication to disarmament by regularly presenting draft resolutions that endorse disarmament efforts to the United Nations General Assembly.

Additionally, Japan has actively engaged in initiatives such as the Non-Proliferation and Disarmament Initiative. Japan’s primary security threat lies with China. The debate in Japan has been limited compared to South Korea. Several senior politicians raised questions about Japan’s lack of nuclear deterrence against China and Russia. Former Japanese Prime Minister Shinzo Abe bluntly talked about the need for Japan to reconsider its options; he suggested a NATO-styled nuclear sharing agreement in an interview. However, the current Prime Minister Fumio Kishida rejected the idea and called it ‘unacceptable’ as it refutes Eisaku’s principles. The debate was also ignited by a nuclear-armed North Korea in the past. Following North Korea’s inaugural nuclear test in 2006, Shoichi Nakagawa, the Chairman of the Liberal Democratic Party’s Policy Research Council suggested initiating a public discourse regarding the acquisition of nuclear arms. In 2017, Shigeru Ishiba, a former defense minister, put forth the idea of accommodating US nuclear weapons on Japanese territory, though this proposition was dismissed by the then-defense minister. The debate is thus not new and is backed by serious security threats faced by Japan from its nuclear-armed neighboring states over time. Russia’s aggressive nuclear stance coupled with China’s rapid military and nuclear modernization pose serious security threats to Japan. Putin suspended peace treaty negotiations with Japan on the matter of Northern territories. Japan believes that China will not be stepping back from its Taiwanese ambitions which are clearly depicted in the One China policy. In December 2022, Japan released its National Security Strategy which states China’s stance on Taiwan as “a matter of serious concern” and “an unprecedented and the greatest strategic challenge.” This further creates tensions between Beijing and Tokyo. Former deputy defense minister Taro Aso spoke of China’s possible invasion of Taiwan as a threat to Japan’s survival. Unlike South Korea, the Japanese public does not support the idea of acquiring nuclear weapons. A national survey conducted in 2019 reveals that 75% of respondents support ratifying the NPT. A small portion of the conservative public still supports the idea of nuclear weapons, considering it a matter of national prestige and giving Japan an upper hand in international politics.

Amid the changing geopolitical situation in the region, both South Korea and Japan view their security in a regional perspective. With North Korea continuously building up nuclear arsenals and increased distrust among the public, the debate on nuclear security has gained prominence. However, Japan’s current government seems committed to its stance on three non-nuclear policies. The Kishida G7 Summit launched at the Hiroshima Peace Memorial Park and the Hiroshima Vision on Nuclear Disarmament reaffirm Japan’s support for global nuclear disarmament. Washington could still have doubts about the regional situation due to the possibility of a nuclear domino effect; if South Korea goes nuclear, Japan will follow it. The mixed signaling and domestic debate have been there for some time. Both states demand an increased role of the United States in the Indo-Pacific. Seoul is looking forward to having a nuclear sharing agreement with the United States similar to that of Europe or having US tactical nuclear weapons on the Korean peninsula. Japan is looking towards increased US support in extended deterrence and possibly, in the near future, could officially debate nuclear sharing options. The current government and public opinion do not support the acquisition of nuclear weapons. The United States needs to reaffirm its support to its allies under its extended deterrence framework.