Historians have largely overlooked the evolution of the North Atlantic Treaty Organization (NATO) despite its ever-expanding role in global affairs. NATO usually appears in historical works on the Cold War as only a minor actor or has been left to be studied by political scientists. Kaplan is the exception to this rule. He has written seven monographs on NATO, each covering different time periods or aspects of the organization. NATO before the Korean War adds to his oeuvre by questioning the orthodox view that NATO remained a toothless and disorganized entity before the Korean War provided the necessary jolt to kick-start its transformation into an effective deterrent to Soviet aggression. As a result, the fourteen-month period between the signing of the North Atlantic Treaty and the outbreak of fighting in Korea has been ignored. But Kaplan argues convincingly that the seed of a fully functioning NATO existed in Article 9 of the treaty that justified the assumption of new responsibilities. Moreover, this book demonstrates that the difficult bargaining over a whole range of issues that took place between Washington and its new allies during this period had resulted in the creation of a regional security organization by the time North Korean forces crossed the 38th parallel. As Kaplan writes, “The O was in NATO from its inception, ineffective and inchoate though its manifestations often were” (149).

NATO before the Korean War adopts an effective chronological structure, with each chapter subdivided thematically. Chapter 1 provides a short summary of the origins of the alliance, covering much of the same material as that contained in Kaplan's previous book, NATO 1948: The Birth of the Transatlantic Alliance (2007). Kaplan's original contribution thus occurs in the subsequent six chapters, through which certain distinct themes permeate. To begin with, Kaplan highlights the divisions regarding NATO that existed within the Truman administration and between the American executive and legislative wings. Another theme is the often fraught relations that developed between the United States and its European allies over the size and shape of NATO forces and the structure of the organization. Kaplan also repeatedly returns to the fissures that emerged between the European member states, specifically Britain and France, who vied for Washington's attention and a leading role within NATO. Underlying many of these problems were Paris's fears of Anglo-American domination and plans for the organization to incorporate a rearmed West Germany.

Yet this book's central message is that practical solutions were eventually found to overcome these many problems. The Truman administration, with Secretary of State Dean Acheson at the forefront, did pursue a proactive NATO policy in spite of the warnings of Secretary of Defense Louis Johnson and others. After much debate, the US Congress did ratify the North Atlantic Treaty and agree to a sizeable Mutual Defense Assistance Program. Bilateral arrangements were ultimately worked out to meet both Washington's desire for integrated forces and the European members’ wishes to have balanced national militaries. The North Atlantic Council did establish on an ad hoc basis a vast array of subsidiary bodies providing NATO with an organizational structure. British and French differences were taken into account with the creation of five regional planning groups. Moreover, while no agreements were reached over West Germany at this stage, this issue was kept sufficiently in the background so that it did not overshadow discussions. As Kaplan concludes, “NATO's infrastructure was in place before the Korean conflict – the system of mutual assistance, the host of committees under the authority of the council, and the beginning of a more centralized governance” (152).

NATO before the Korean War is clear and concise, written with Kaplan's distinctive and authoritative voice throughout. Still, while Kaplan justifies his American-centric approach on the grounds that Washington dominated NATO throughout this period, the roles played by the other members, with the exception of Britain and France, are largely absent. Further research on these stories would add even greater colour to the history of NATO. Additionally, the author himself admits that the Korean War still provided the necessary catalyst to transform NATO into a real deterrent to Soviet aggression. Given the pace of developments outlined in this book, and the problems that still needed to be resolved, it appears very unlikely that NATO would have achieved this status for a considerable period of time if North Korea had not attacked South Korea. Nonetheless, Kaplan's latest book adds invaluable detail to our knowledge of the organization's challenging first fourteen months.