This article focuses on collective security and the prohibition on the use force in times of global transition. It examines whether current threats to the so-called rules-based international order—the crises in Libya, Syria and the Ukraine; climate change and the rise of populism—present novel challenges to the normative framework of the use of force or whether they simply represent the latest manifestations of challenges that have existed in similar forms in the seven decades since the adoption of the UN Charter. The article concludes that it is unlikely that the past decade saw the beginnings of a more fundamental backlash against the normative framework on the use of force and that the rules in this area of international law are robust enough to withstand contemporary challenge.