Alliances are traditionally seen as military pacts formed by states to counter common threats. But alliances are also often valued as political institutions that allow states within them to pressure and do business with one another. Weaker or smaller alliance partners gain some access to the strategic decision-making of the leading state, and the leading state gains some leverage over the actions of junior partners. This valuable study explores the logic of these intra-alliance power relationships, looking in particular at moments when states try to use alliance ties to restrain risky military actions by their partners. In a wide-ranging survey of alliances in Europe and Asia over the last century, Pressman finds that the "restraint motive" for alliance creation is as important as the "mutual protection" motive. Case studies focus on the United States' alliance relations with the United Kingdom and Israel -- probing episodes such as the 1967 Arab-Israeli war, the Israeli invasion of Lebanon in 1982, the U.S. nonintervention in Indochina in 1954, and the British intervention in the Suez War of 1956. Pressman finds that powerful states can use alliances to thwart the military actions of weaker partners if they are willing to mobilize their power to do so, and powerful states can go to war despite the misgivings of their junior alliance partners. The value of the book is that it underscores the view that alliances are not just protection pacts but also a form of political architecture that creates "institutional pathways" for the management of wider geopolitical relationships. In other words, alliances are as much about allies as they are about enemies.