Recent events including rapid nuclear modernization of North Korea and China and increasing fear of nuclear escalation in Ukraine have led to renewed attention to nuclear politics in East Asia. In this context, this paper aims to address one of the most distinguished concepts in nuclear politics and its relevance to East Asia’s security environment: the stability-instability paradox. Specifically, this paper seeks to address the two following questions. Is the stability-instability paradox applicable to the inter-Korean security environment? If so, by what mechanism will the stability-instability paradox work in the region? Through theoretical analysis and a case study on the bombardment of Yeonpyeong Island in 2010, this paper yields two findings. First, while not yet fully applicable, the logic of the stability-instability paradox is increasingly becoming relevant in the inter-Korean security environment. Second, the stability-instability paradox in the region is likely to work through the mechanism of the ‘red-line model’, which entails relatively little danger of intentional nuclear escalation.