This volume examines the growing rise of transactionalism in US foreign policy and its implications for transatlantic relations and European security. Bringing together scholars and practitioners from seven countries, the volume explores why American statecraft has become more conditional, interest-based, and selective toward its closest allies, and how European states are responding to uncertain US security commitments. Combining perspectives from international relations, political science, war studies, and diplomatic history, the US and European contributors analyse transactionalism as both a mode of political practice and a broader expression of geopolitical change. The volume examines how structural pressures, domestic political fragmentation, leadership styles, and deeper ideational shifts inside the United States interact to reshape the Atlantic relationship. It also assesses Europe’s responses through military reconstruction, strategic adaptation, differentiated integration, and political reordering. Rather than predicting transatlantic collapse, this book argues that the Atlantic order is undergoing a period of sustained stress: contested, recalibrated, yet remarkably resilient. This book will be of much interest to students of transatlantic relations, US foreign policy, European politics, and International Relations.
