Dodd, LyndaNelson, Sarah Francesca Saldivar2025-07-312025-07-312025-04-01https://theses-dissertations.princeton.edu/handle/88435/dsp01vh53x0184This thesis explores three explanations for the breakdown of 21st-century American nuclear strategy, ultimately arguing that China’s emergence as a nuclear superpower drives this collapse. China’s economic, technological, and military prowess uniquely position it as a strategic partner to Russia, an alliance that poses unprecedented challenges to US nuclear weapons policy. This thesis uses a process-tracing-inspired methodology to analyze three key American diplomatic tools: the NPT, the New START, and the US-China 123 Agreement. It finds that geopolitical tensions undermine the effectiveness of nuclear agreements, as international actors often exploit weak provisions and face minimal accountability. Accordingly, 21st-century American nuclear weapons strategy must reckon with the deepening interdependence between geopolitical rivalry and nuclear arms control, particularly concerning the US-China atomic relationship. This thesis concludes by providing policy recommendations that emphasize (1) treating China as a central nuclear actor, (2) strengthening enforcement mechanisms, and (3) prioritizing multilateral diplomacy.enPrinceton University Senior Theses