Almost as if according to some natural law, in every century there seems to emerge a country with the power, the will, and the intellectual and moral impetus to shape the entire international system in accordance with its own values. In the seventeenth century, France under Cardinal Richelieu introduced the modern approach to international relations, based on the nation-state and motivated by national interest as its ultimate purpose. In the eighteenth century, Great Britain elaborated the concept of the balance of power, which dominated Europeandiplomacy for the next 200 years. In the nineteenth century, Metternich’s Austria reconstructed the Concert of Europe and Bismarck’s Germany dismantled it, reshaping European diplomacy into a coldblooded game of power politics. In the twentieth century, no country has influenced international relations as decisively and at the same time as ambivalently as the United States. No society has more firmly insisted on the inadmissibility of intervention in the domestic affairs of other states, or more passionately asserted that its own values were universally applicable. No nation has been more pragmatic in the day-to-day conduct of its diplomacy, or more ideological in the pursuit of its historic moral convictions. No country has been more reluctant to engage itself abroad even while undertaking alliances and commitments of unprecedented reach and scope.