The US and South Korea: The Trouble with Nuclear Assurance

Abstract As US officials have grown more anxious about the credibility of extended nuclear deterrence, they have placed renewed emphasis on nuclear-assurance measures. The hope is that closer exercises and consultations can reassure allies, strengthen deterrence postures and reduce the risk that an ally could pursue their own nuclear weapons. However, recent developments in the US–South Korea alliance suggest that nuclear assurance is not only ineffective at reassuring Seoul but may also be fuelling proliferation risks. By raising the salience of nuclear weapons within the alliance, nuclear assurance reinforces the fiction that South Korea’s defence depends on nuclear use. Misunderstanding the risks and potential of nuclear assurance has fuelled calls for a South Korean nuclear-weapons programme and obstructed the alliance’s ability to adapt and improve its deterrence posture.