The United States–Republic of Korea Alliance: Strengthening Extended Nuclear Deterrence in a Shifting Strategic Landscape

For the past seven decades, the United States’ extended deterrence commitment to the Republic of Korea (ROK) has been critical to advancing two central aims of the alliance: (1) deterring North Korean aggression and (2) preventing nuclear proliferation by giving South Korea a credible alternative to developing its own nuclear arsenal. Today, however, a shifting geopolitical environment has introduced new areas of uncertainty into the alliance.

The Asan Institute for Policy Studies and CSIS engaged in a joint project from late 2025 to early 2026, including a full-day workshop to assess extended nuclear deterrence cooperation within the U.S.-ROK alliance. The select group of experts and former officials discussed the credibility of U.S. extended deterrence commitments and brainstormed ways to strengthen these commitments amid heightened uncertainty and evolving security challenges in the region. The key observations and recommendations of the project recorded in this report do not necessarily reflect the views of every participant in the study, or the positions of either organization.    

This report was made possible through the support of CSIS and the Asan Institute.