from Asia Program

The United States–South Korea Alliance

Why It May Fail and Why It Must Not

Foreign policy analyses written by CFR fellows and published by the trade presses, academic presses, or the Council on Foreign Relations Press.

The alliance between the United States and South Korea has endured through seven decades of shifting regional and geopolitical security contexts. Yet it now faces challenges from within. Domestic political turmoil, including deepening political polarization and rising nationalism in both countries, has cast doubt on the alliance’s viability—with critical implications for the balance of power in East Asia.

Scott A. Snyder provides an authoritative overview of the internal and external pressures on the U.S.–South Korea alliance and explores its future prospects. He argues that nationalist leaders’ accession to power could put past successes at risk and endanger the national security objectives of both countries. In the United States, “America First” nationalism favors self-interest over cooperation and portrays allies as burdens or even free riders. “Korea first” sentiments, in both progressive and conservative forms, present the U.S. military presence in South Korea as an obstacle to Korean reconciliation or a shackle on South Korea’s freedom of action. Snyder also examines North Korea’s attempts to influence South Korean domestic politics and how China’s growing strength has affected the dynamics of the alliance. He considers scenarios in which the U.S.-South Korea relationship weakens or crumbles, emphasizing the consequences for the region and the world. Drawing on this analysis, Snyder offers timely recommendations for stakeholders in both countries on how to preserve and strengthen the alliance.

More on:

South Korea

East Asia

Security Alliances

Timeline: The U.S.-South Korea Alliance, 1950–2023

More on:

South Korea

East Asia

Security Alliances

Reviews and Endorsements

Scott A. Snyder’s book is a bracing reminder that a U.S.–South Korea alliance cannot be taken for granted. Especially timely is Snyder’s detailed discussion of the effect of political polarization, populism, and nationalism in both countries on the future of the alliance. He makes a convincing case for why the alliance continues to matter, more than ever, and how to ensure its vitality going forward.

Kathleen Stephens, former U.S. Ambassador to the Republic of Korea

The U.S.–ROK alliance is back on track under the Biden and Yoon administrations. However, during the Trump and Moon administrations, the alliance became vulnerable. Snyder rightly points out the threats to the alliance from within. This is definitely a must-read book for both practitioners and researchers.

Cheol-Hee Park, chancellor of the Korea National Diplomatic Academy

Snyder is the leading U.S. scholar on the alliance with South Korea. There is much to learn from this book, but the overall theme is particularly compelling: that political polarization at home—on both sides—poses risks to the alliance.

Stephan Haggard, author of Developmental States

In The United States–South Korea Alliance, Snyder once again raises the bar on scholarship covering contemporary Korean affairs. Coinciding with the seventieth anniversary of the alliance, this future-oriented study investigates the domestic political currents and international pressures facing both South Korea and the United States to understand where the alliance is heading and what remains at stake.

Andrew Yeo, author of Asia’s Regional Architecture: Alliances and Institutions in the Pacific Century

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