Alliances have been the cornerstone of U.S. foreign relations since the 1940s. Even now, they remain the foundation for global security cooperation. But in this provocative book, Menon asserts that such formal military ties are destined to fade away. It is not a return to isolationism that will drive the dissolution of alliances but rather a slow -- and, to Menon's mind, welcome -- strategic reorientation of the United States' global position, with more informal and shifting alignments of states. Menon's thesis is based partly on his reading of the past: the United States has always been ambivalent about security commitments and maintaining a long-term overseas military presence, a national orientation only temporarily overcome by the Cold War. The new security environment, Menon goes on to argue, marked by the rise of terrorism and the absence of threatening great powers, makes alliances dispensable. Moreover, Washington's European and Asian allies are now economically revived and able to provide for their own security. In the end, Menon offers a clear picture of the global shifts that have thrown the role of alliances into question, but his argument that the costs of alliances are rising relative to their benefits is less convincing. Nor does he explore the role of the U.S. alliance system in facilitating cooperation among the advanced democracies. Today's alliances may have outlived their historical causes, but their usefulness remains.