This article, challenges the fundamental assumption of the global non-proliferation regime, that limiting the spread of nuclear weapons leads to peace, and argues instead that nuclear deterrence is the most effective mechanism for preserving national sovereignty and preventing war. Drawing on realist theory, deterrence models, and extensive comparative analysis of case studies, this research shows that non-nuclear-weapon states have been vulnerable to foreign intervention, regime change, and coercive diplomacy. In contrast, nuclear-weapon states have been able to deter foreign aggression. Moreover, competing nuclear powers have consistently avoided full-scale war. These patterns suggest that nuclear weapons, even among adversaries, induce caution and strategic restraint, making deterrence a stabilizing force. Using a comparative qualitative methodology, combining process tracing, dynamic analysis, and comparative qualitative analysis, this paper examines the mechanisms linking nuclear power to peace and strategic immunity. From a theoretical perspective, it introduces the concept of “proliferation justice,” a framework that critiques the structural inequality embedded in the Nuclear Non-Proliferation Treaty (NPT) and advocates for regulated, threat-based access to nuclear deterrence for vulnerable states. Ultimately, the paper argues that peace is achieved not
through disarmament or normative consensus, but through the credible threat of retaliation.