Regime change of a different kind: Exploring adaptation in the nuclear regime

The dissertation explores the emergence of the Proliferation Security Initiative (PSI)---a 2003 Bush administration initiative to interdict the transfer of weapons of mass destruction and related materials to states and non-state actors. It explains the PSI's emergence as a non-legally binding, broadly defined political pledge in the context of the nuclear nonproliferation regime. It adopts a rational-choice institutionalist approach, examining the elements of legality (binding or non-binding) and precision (precise or broad) with respect to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the Zangger Committee (ZAC), the Nuclear Suppliers Group (NSG), and the PSI.;It examines the negotiating history of the NPT to determine the reasons for its design as a legally-binding treaty, with varying degrees of precision. Then, it explains the emergence of the ZAC and the NSG as mechanisms to clarify ambiguity in the NPT's Article III, and accounts for the legality and precision of their design.;The dissertation argues that the PSI emerged to fill a critical gap in the nuclear nonproliferation regime. It became an enforcement mechanism to supplement the NPT, ZAC, and NSG. The dissertation explains the reason for the PSI's design, finding that conditions of uncertainty, urgency, and a low enforcement problem account for its non-binding and broad nature. It finds that where the enforcement problem was high, the Bush administration employed two strategies: first, it deliberately excluded important stakeholder states it felt would stymie agreement---inviting them to join only after the agreement had been made; and second, it negotiated legally-binding and precise ship boarding agreements to underpin the PSI framework.;Based on these findings, the dissertation posits how the elements of legality and precision can contribute to flexibility in international agreements. It concludes with policy prescriptions for the PSI's strengthening.