The Nuclear Non-Proliferation Treaty (NPT) is a central element of the global nuclear order, the primary goal of which is to prevent nuclear war. But this understanding is being threatened by a number of developments. Frustration about the lack of nuclear disarmament and concerns about humanitarian consequences of nuclear weapons led to the negotiation of the Treaty on the Prohibition of Nuclear Weapons (TPNW). The new treaty has further exposed existing fault lines within the NPT and exacerbated unresolved conflicts over the proper approach to disarmament and the weighting of the NPT pillars. Currently, disagreements over the compatibility of the two treaties and the approach to the TPNW in particular divide the membership of the NPT. At the same time, real proliferation cases test the regime’s ability to act, as norm enforcement is regularly hampered by interference from the great powers. These developments—the absence of genuine disarmament, disputes among NPT members, competition between the TPNW and the NPT, and actual nuclear proliferation—are part of a comprehensive crisis and destabilization of the non-proliferation regime. We argue that three developments are necessary to restabilize the regime: a cooperative resolution of the power struggles among the major powers; a depolarization of the inter-group divisions in the NPT; and a return to the principle of nuclear war prevention as a common maxim for action.