This month, the Tenth Review Conference of the Non-Proliferation Treaty (NPT) is taking place in New York City. The meeting of states parties, postponed four times because of the Covid pandemic, had originally been scheduled for April 2020. With Russia’s war of aggression against Ukraine, the geopolitical context has since deteriorated to the point where progress on nuclear disarmament and nonproliferation seems almost impossible. The war and Russia’s nuclear threats are fostering a renaissance of nuclear deterrence and rearmament and are threatening to deepen pre-existing fissures in the NPT. To counter the looming erosion of this cornerstone of global arms control, we need to acknowledge the darker side of nuclear deterrence that the Ukraine war is exposing. Understanding the current crisis as a crisis of nuclear deterrence can open up opportunities for de-escalation, disarmament and arms control – similar to the transformative effects of the Cuban Missile Crisis during the Cold War.