The United States is by circumstance and design an emergent global empire, the first in the history of the world. Prior empires have had frontiers and boundaries, although occupying large expanses of territory, and exerting control from a distant center that due to available technologies of communication and transportation were further away in time than is any part of the global from Washington. In purely temporal terms, the American Empire is thus smaller than earlier great empires associated with China, the Ottomans, the Persians, the Austro-Hungarian, and the overseas empires of the British, French, Dutch, Spanish, and Portuguese. It is important to appreciate the consequences of an empire of global scope. Such an empire, to the extent that it is established and sustained without significant resistance, raise a special challenge to world order. Over the course of modern history, in particular, stability in international relations has been maintained primarily by...