Assessing Red Lines in the US-China-Taiwan Trilateral Relationship

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The idea of “red lines” has become a favorite catch-all term to discuss coercion, grey area tactics, and escalation. Particularly in the case of the US-China relationship over Taiwan, policymakers and scholars use red lines as a shorthand to conceptualize crisis thresholds, a point where ambiguity ends, and the stakes are highest. But there is limited consensus on the definition of red lines, and even less consensus on where red lines are between the US and China. This thesis creates a theoretical framework for understanding red lines and applies to it to the US-China-Taiwan case to explore how the US and China treat red lines in practice, and why some red lines fail where others succeed. Drawing on a set of case studies of Taiwan-centered red lines, I analyze how their integrity has evolved, contextualizing violations and enforcement through a typology. I assess red lines based on four main components: a situational threshold, demand, threat, and justification, and suggest that the strength of a red line is highly dependent on having all four components. Particularly in an era of grey area conflict between the US and China, understanding how to draw red lines most effectively, and which red lines are de jure versus de facto, is essential for preventing miscommunication and unwanted escalation.


Type of resource text
Date modified December 5, 2022
Publication date June 3, 2022; June 2, 2022


Author Kohatsu, Hannah
Thesis advisor Mastro, Oriana
Degree granting institution Stanford University
Department Center for International Security and Cooperation


Subject red lines
Subject Deterrence (Strategy)
Subject grey zone
Subject China
Subject Taiwan
Subject International relations
Genre Text
Genre Thesis

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Kohatsu, H. (2022). Assessing Red Lines in the US-China-Taiwan Trilateral Relationship. Stanford Digital Repository. Available at


Stanford University, Center for International Security and Cooperation, Interschool Honors Program in International Security Studies, Theses

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