Ryo Sahashi is a nonresident scholar in the Asia Program at the Carnegie Endowment for International Peace and a tenured full professor of international relations at the University of Tokyo. His research focuses on U.S.–China strategic rivalry, Japan’s foreign and security policy, Korean Peninsula issues, and the transformation of the Indo-Pacific regional order. He is currently leading a multi-year project examining the continuity and evolution of East Asian order from the early modern period to the present.

Sahashi plays an active role in policy debates in Japan and the region. He serves on a number of government advisory panels, including the Council on the Use of Real Estate under the Cabinet Secretariat and the Advisory Board for Promoting Science and Technology Diplomacy at Japan’s Ministry of Foreign Affairs. He previously served on the Japan–ASEAN Expert Panel established by the Prime Minister’s Office and represents Japan on the ASEAN Regional Forum’s Experts and Eminent Persons group. He sits on the boards of the Japan Center for International Exchange and the Japan Association of International Affairs and serves on the board of advisors for the National Bureau of Asian Research. He is also a visiting fellow of the Keidanren Policy Research Institute and principal investigator for U.S. affairs at the Japan Institute of International Affairs.

Sahashi’s publications span the fields of international politics and regional security. His books include US–China Rivalry: A Shift of American Strategy and Divided Worlds (Chuko, 2021) and East Asian Order After the Cold War (edited, Keiso, 2015). His recent peer-reviewed articles have appeared in Pacific Affairs—including a 2024 article co-authored with Ayumi Teraoka on Japan’s defense transformation—Journal of Contemporary China, Contemporary Politics, and China International Strategy Review. He also serves on the book review committee of the Yomiuri Shimbun.

Sahashi has held visiting appointments at Australian National University, Stanford University, the Instituto Tecnológico Autónomo de México (ITAM), the Wilson Center, Seoul National University, and the École des Hautes Études en Sciences Sociales (EHESS) in Paris. He received his BA from International Christian University and his PhD from the University of Tokyo.