Date of Award

Spring 2021

Document Type


Degree Name

Doctor of Philosophy (PhD)


Political Science

First Advisor

Monteiro, Nuno


Why do advanced nuclear states agree to legally forswear nuclear weapons? Many international relations studies have explored why states seek to develop nuclear weapons. Yet, the literature does not address why states would participate in multilateral nuclear arms control treaties that tie their hands against doing so. This gap in the existing scholarship matters because nuclear weapons are one of few tools that can effectively guarantee a state's sovereignty and national survival. My dissertation disaggregates the process of entering multilateral nuclear arms control treaties into two phases. Previous studies have discussed either treaty signature or ratification, overlooking the often lengthy delays between them. However, motivations for signing and ratifying are often distinct because these actions carry different legal weights and political consequences. I discover that signing a treaty can reflect a variety of "type signaling" motivations about a state's views on the distribution of power the agreement reifies. Indeed, signatories signal to the international community their advocacy for the treaty or subordinate status to a powerful patron that compels them to sign. Non-signatories signal a desire for enhanced status or interest in considering the nuclear option. But ultimately, states will only engage in legal “commitment signaling” not to pursue nuclear weapons through ratification if their security environment permits it. Accession to a treaty once it has already entered into force—and signature is no longer possible—requires a “joint signal” pertaining to both necessary conditions. To demonstrate the applicability of my theory, I investigate four case studies of states with advanced civilian nuclear energy capabilities or weapons proliferation aspirations. I examine the causal pathways that led Brazil, Egypt, Japan, and Romania to embrace the Nuclear Nonproliferation Treaty (NPT) of 1968 and the Comprehensive Nuclear-Test-Ban-Treaty (CTBT) of 1996. These states acted in accordance with the two-step process of type and commitment signaling described in my theory despite varying regime types, alliance commitments, levels of industrialization, and more. The case studies shed new light on international nuclear politics by drawing on diverse sources, including archival documents and original elite interviews I conducted with decision-makers. Taken together, this dissertation makes three primary contributions to the scholarly and policy-making domains. First, it offers a new process-based theory explaining an understudied phenomenon in international security. Second, it provides evidence and insights that challenge dominant narratives surrounding historical cases of legal nuclear forbearance. Third, it suggests novel approaches to understanding incentive structures behind differing levels of commitment to multilateral nuclear arms control.