Executive Summary
The April 2023 Washington Declaration is one of the most significant developments in the United States (US)-South Korea alliance to have taken place during the Biden-Yoon era. This new bilateral agreement included a reassertion of Seoul’s status under the US nuclear umbrella, an acknowledgement by South Korea of its confidence in this extended deterrence and a reaffirmation of its commitment to nuclear nonproliferation, as well as a number of discrete commitments by the two allies to enhance cooperation and deterrence—most notably the establishment of a Nuclear Consultative Group (NCG). In this working paper we provide an in-depth examination of the Washington Declaration through a review of official government statements and documents, media reports, and secondary policy and academic literatures. In Section One, we find that the Washington Declaration was agreed upon within a context of heightened threat perceptions around North Korea’s advanced nuclear and ballistic missile capabilities, active debate about nuclearization in South Korea, and tensions in the US-South Korea alliance. In Section Two, we map out diplomatic and civil society responses to the agreement among key stakeholders: the allies South Korea and the US; and their rivals in North Korea, China, and Russia. In Section Three, we establish that the allies’ commitment under the Washington Declaration to enhance consultation and planning, deploy US strategic military assets, and engage in joint exercises and training, has largely been fulfilled. However, in Section Four, we find that this agreement has had limited impact on South Korea’s perceptions of the US security guarantee due to problems with the definition and communication of its key commitments, the substance of the agreement, and its weak durability. In the long-term, we argue that the Washington Declaration has not done enough to restrain South Korea’s nuclear ambitions. In the final section, therefore, we offer nuclear nonproliferation-sympathetic decision makers in the US three key recommendations. First, that the US should publicly make clear the distinction between key features of the Washington Declaration’s NCG and the NATO Nuclear Planning Group (NPG) to avoid conflation between the US’ commitments within each alliance framework. Second, that the US should take a more holistic approach to the alliance that takes the interplay between economic security, military security, and trust between allies into account. Third, we argue that the US should recognize the limits of its ability to unilaterally safeguard nuclear nonproliferation in South Korea, and additionally begin to work with its other Indo-Pacific allies, partners—and even rivals—to reinforce Seoul’s security, promote public education, and create a regional political context in which nuclear saliency is reduced.
