The Second World War put an end to America's historical isolation from international power politics, and so also to the long-standing American defiance of the Realist ideology that shaped Old World affairs. The advent of transoceanic military technologies, now wielded by menacing states such as Nazi Germany and the Soviet Union, made Americans more receptive to the Realist idea that international relations is about fear and survival. The American Realists Reinhold Niebuhr, Hans Morgenthau, and Kenneth Waltz developed a modern strategic framework that sought to introduce American leaders and the educated public to these harsher realities of international politics. They emphasized a clear-eyed, cold approach to the play of interests, egotism, and the drive for power in world affairs-a struggle in which the threat of major war remained, in the end, the only legitimate currency. Yet even as Americans began to accept this new Realism, thermonuclear weaponry threatened to make it absurd. A major war to |