In this detailed account of NATO’s first year, Kaplan shows that the launch of the alliance is best understood not as a watershed moment for American internationalism but as just one part of the long path the United States had traveled from isolationism to engagement. Kaplan chronicles the Truman administration’s navigation of the tricky politics of ratifying the treaty and bringing the alliance to life. The book’s most interesting element is the story it tells about how American proponents of NATO were able to cast the treaty less as a military alliance and more as a tool of U.S. postwar internationalism, creating a partnership that would bolster European stability and allay British and French fears of a resurgent Germany. The alliance emerged not in a single moment of creation but through a long and tedious process of negotiations marked as much by improvisation as by design. Nonetheless, as Kaplan argues, the two sides ultimately discovered the terms of a grand bargain: the United States would commit itself to helping rebuild and protect Europe, and the Europeans would overcome their differences and forge a new Atlantic system.