Weapons of peace or instruments of catastrophe? Rethinking nuclear deterrence, legitimacy, and security in light of humanitarian evidence

This article advances a policy-oriented argument about the legitimacy and sustainability of nuclear deterrence in light of the expanding scientific and humanitarian evidence base on the consequences and risks of nuclear weapons. Drawing on research developed through the Humanitarian Impacts of Nuclear Weapons Initiative and on arguments elaborated within the Treaty on the Prohibition of Nuclear Weapons (TPNW), particularly the 2025 report on the security concerns of states parties under the TPNW, the article argues that contemporary knowledge about nuclear weapons consequences has shifted the terms of the nuclear deterrence debate for non-nuclear states. From this perspective, the central problem is no longer only whether nuclear deterrence can be defended as a strategic doctrine, but whether it remains politically, legally and ethically legitimate when assessed against evidence of catastrophic humanitarian harm, environmental disruption, food insecurity, health-system collapse, transboundary effects and systemic global risk. The article synthesizes existing scientific, legal and policy literature to articulate a critical perspective on nuclear deterrence and to promote policy arguments developed in the TPNW framework that articulate the security perspective of states not relying on nuclear weapons. It contends that the nuclear deterrence discourse has not adequately absorbed the implications of humanitarian evidence and nuclear risk research, creating an asymmetry between what is empirically known about nuclear consequences and what is assumed about nuclear deterrence stability. The article concludes that nuclear security debates must be rebalanced by integrating humanitarian evidence, security concerns of non-nuclear-weapon states and risk-based arguments into mainstream policy deliberation.