Kathleen J. McInnis

Russia's February 2022 invasion of Ukraine triggered the bloodiest war in Europe since World War II and raised significant questions about the United States' role in Europe. This CSIS report examines the U. S. force posture in Europe---including the military capabilities, personnel, infrastructure, and agreements that support defense operations and plans---and makes recommendations for future U. S. posture. It finds that the United States needs a robust, long-term military force posture in Europe, focused on the North Atlantic Treaty Organization's (NATO) eastern flank, to deter future Russian aggression.

This book identifies contemporary military coalition defections, builds a theoretical framework for understanding why coalition defection occurs and assesses its utility for both the scholarly and policy practitioner communities. Drawing upon the author’s own experiences managing the Afghanistan coalition for the Pentagon, the volume builds a relevant policy and practical understanding of some of the key aspects of contemporary coalition warfare. Ultimately, it concludes that coalition defection is prompted by heightened perceptions of political and military risk. Yet the choice of how to defect— whether to completely withdraw forces or instead find another, less risky way to participate—is largely a function of international and alliance pressures to remain engaged.