ASIA WATCHChanging State Perception of Nuclear Deterrence in Japan and South Korea
Japan and South Korea face the combined threat of an increasingly assertive China and a progressively more destabilizing North Korea, not to mention a Russia which has resumed its role as a Pacific power. The US has enhanced its engagement with its East Asian partners in nuclear planning and consultation mechanisms. The prospects of indigenous nuclear weapons acquisition by Japan and South Korea, though, cannot be ruled out.
In 2021, after Prime Minister Fumio Kishida came to office, Setsuko Thurlow, an atomic bomb survivor and well-known anti-nuclear weapons activist, urged him to sign the newly-negotiated Treaty on the Prohibition of Nuclear Weapons (TPNW).1 She blamed the Japanese government for seeking continued protection from the very weapons that had been twice used on its soil by the very power that now guaranteed Japan’s security. She urged Prime Minister Kishida to sign the treaty and lead the campaign against nuclear weapons.
Japan however did not sign the TPNW and the nuclear umbrella of the United States remains intact. The nuclear program of North Korea continues to churn, with little to no oversight by the International Atomic Energy Agency (IAEA). Russia, the world’s largest nuclear-armed state, continues to threaten the deployment of tactical weapons against Ukraine. China modernizes its arsenal and refuses to participate in arms control talks until the US and Russia reduce their arsenals first.2
Kishida’s hesitation to sign the TPNW and commit to a non-nuclear stance reflects the threat perception held by East Asian democracies such as Japan and South Korea, as they face the combined threat of an increasingly assertive China and a progressively more destabilizing North Korea, not to mention a Russia which has resumed its role as a Pacific power.
Evolving Nuclear Policy
Historically, Japan and South Korea were early adopters of norms against nuclear proliferation. Japan is a signatory to all major international treaties relating to nuclear weapons (with the exception of the TPNW), as is South Korea. However, in the immediate post-war period, both had very divergent views on nuclearization. Japan aligned itself closely to a staunchly negative stance towards nuclear weapons, while South Korea attempted to actually pursue its own domestic nuclear weapon, even as both were protected by the extended nuclear deterrence umbrella of the US.
