This book explores the largely neglected issue of responses to the US Strategic Defence Initiative (SDI, or the 'Star Wars' missile defence programme) across NATO. The chapters here explore the reactions of different Western allies to the announcement of the SDI in 1983 and especially the 1985 invitation to participate. While existing studies have explored the origins of the American programme and the role it may have played in ending the Cold War, this volume breaks new ground by considering the impact of the SDI on transatlantic relations in the 1980s. Based on newly available archival sources, this volume re-evaluates the responses of eight NATO member-state governments, as well as the Soviet leadership, to the SDI. In addition to looking at ‘top-down’ governmental reactions, the volume also explores the ‘bottom-up’ response to the SDI of civil society and peace activists on both sides of the Atlantic. The volume examines how the American initiative – derisively named ‘Star Wars’ by its detractors – provoked a crisis in relations with its allies during the final decade of the Cold War and how those tensions within NATO were ultimately resolved. This book will be of much interest to students of Cold War history, strategic studies, foreign policy and international history.