PurposeThis paper aims to provide a case study of complex conflict management within the arms race on the Korean Peninsula. Exploring the complex nexus of nuclear weapons, asymmetry and a qualitative arms race, the study explains how the arms race between Seoul and Pyongyang has promoted stability on the Korean Peninsula.Design/methodology/approachPresenting the limits of arguments that the US security guarantee is the factor that saved the two Koreas from going to war again, this paper explores the utility of the inter-Korean arms race as a stabilizer that promotes indirect negotiations. While presenting Korean anomalies, this paper analyzes the three stages of the inter-Korean arms race – especially its nuclear weapons, its asymmetry and the nature of arms races – and provides extant explanations on the causes and consequences of the qualitative arms race. These key elements drive the states’ strategic motives.FindingsUsing the case of the inter-Korean qualitative arms race and US extended nuclear deterrence on the Korean Peninsula, the study shows the complexities of conflict management today. This paper identifies three contributing factors – US nuclear weapons, asymmetry and the qualitative characteristic of the arms race – to explain the enduring stability on the peninsula despite the arms race’s intensification. The paper finds that although US nuclear-extended deterrence plays a critical role, it does not capture the full context of the ongoing, dynamic inter-Korean arms race; a prolonged arms race between the two Koreas has become a new regularity; the qualitative characteristic of the inter-Korean arms race, which is driven by technological advancement, contributes to stability in the arms race; and as the constant mismatch in priority technologies becomes more severe, the changes to the existing asymmetry could increase instability.Originality/valueThis paper offers a diverse perspective to the literature on conflict management and captures the complexities of 21st-century conflict management. Through a thorough examination of the inter-Korean arms race, it brings readers’ attention to the nested dynamics within the arms race and shows how an intensifying arms race can promote stability. Furthermore, the paper explains the implications for potential instability – fueled by the comprehensive mix of a dynamic qualitative arms race and the US extended nuclear deterrence – in the Indo-Pacific region.