The United States’ (US) nuclear umbrella over South Korea and Japan has long been a subject of debate. On the one hand, the United States supports the denuclearization of the Korean Peninsula, while on the other hand, it provides a nuclear umbrella of protection to South Korea and Japan. This has called into question the future of the US nuclear commitment to its allies. Under what conditions can nuclear deterrence be maintained without South Korea or Japan developing nuclear weapons? What are the consequences of nuclear proliferation in East Asia?
These questions are becoming increasingly important in an environment where North Korea is conducting nuclear tests and missile provocations despite international efforts to prevent it from developing weapons of mass destruction. Changes in North Korea’s security environment are forcing South Korea and Japan to evolve their security postures, and there is a growing view in both countries that a nuclear sharing arrangement with at least the United States is necessary for deterrence and assurance against North Korea’s weapons of mass destruction. These steps are being taken at a time of growing threats posed by North Korea, China and Russia in the region.
Deputy Secretary of State Kurt Campbell said that South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida jointly deserve the Nobel Peace Prize for their ‘political courage’, referring to the two leaders’ attempts to improve bilateral relations last year. Campbell focused on the achievements in trilateral cooperation between South Korea, Japan and the United States at a forum hosted by the Hudson Institute, a Washington-based think tank, on Wednesday, 24 April 2024. The US commitment to security in the Asia Pacific region plays a central role in its relations with its allies in the region. In this context, the US nuclear deterrence policy aims to reinforce its security commitment to its allies in the region. Campbell’s statements emphasize the commitment of the US extended deterrence policy to protect its non-nuclear allies.[1]
In recent years, Seoul and Tokyo’s bilateral relations have deteriorated due to historical disputes, such as the payment of compensation to Korean citizens for forced labor during the Second World War and the trade dispute that began in the summer of 2020. In March 2023, following a bilateral summit in Tokyo, Yoon and Kishida agreed to normalize relations, along with the two countries’ General Military Information Security Agreement. The two leaders met several times to try to mend relations, paving the way for the historic trilateral Camp David Summit in August 2023, which was attended by US President Joe Biden. “It was remarkable to see that the leaders of Japan and South Korea both recognized the incredibly difficult historical issues and the determination of interest groups and political factions in both countries to ignore the current history,” Campbell said in an interview.[2]
The risk of conflict in the Asia Pacific is becoming a concern for countries outside the region, as well as for the United States’ security partners and key allies in the Asia Pacific – Australia, Japan, South Korea and the United Kingdom.
The concerns of these security partners are compounded by concerns about Washington’s continued commitment to the region after the US elections in 2024. The prospect of a second Trump administration has pushed US allies to seek as much reassurance from the United States as possible while the more accommodating Biden administration is in power. In line with strengthened alliance commitments, enhanced military coordination and deterrence measures are envisioned to continue in the region. A notable example of this strategy is Australia’s move to acquire nuclear-powered submarines from the US and UK through the AUKUS agreement.
South Korea, on the other hand, sought and received additional assurances through the Washington Declaration as part of the US extended deterrence commitments. In addition to ballistic missile submarines and B-52 bombers, the US has established a new bilateral Nuclear Advisory Group, while Japan has issued a series of new security documents to ‘pave the way for strategic, institutional and tactical integration’ with the US.[3]
The US security partners in the Asia Pacific are making multidimensional decisions on deterrence. However, dialogues with the active actors in the region, China and North Korea, seem to be insufficient for a stable deterrence. In short, current US, Japanese and South Korean policies are risky. In particular, there is a lack of understanding among actors in the Asia-Pacific about how deterrence works and the stabilizing role of assurances in times of high tension in a multipolar system.
Asia-Pacific and European countries feel compelled to come together with other allies to strengthen their own defenses as well as to develop multilateral deterrence measures. They are accelerating their efforts to reduce their energy and financial dependence on Russia and China. This requires long-term multilateral efforts to develop alternative suppliers of raw materials and producers of manufactured goods.
[1] “U.S. deputy secretary of state says Yoon and Kishida deserve Nobel Peace Prize”, Korea JoongAng Daily, https://koreajoongangdaily.joins.com/news/2024-04-25/national/diplomacy/US-deputy-secretary-of-state-says-Yoon-and-Kishida-deserve-Nobel-Peace-Prize/2033779, (Access Date: 26.04.2024).
[2] Aynı yer.
[3] Petersson-Ivre, J., Meier, O., Ogilvie-White, T., & Paul, R. (2024). Balancing deterrence with assurances–policy coordination between security partners in the Asia-Pacific.
