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The Emerging Structure o f International Politics IF o r more than three hundred years, the drama of modern history has turned on the rise and fall of great powers. In the multipolar era, twelve great powers appeared on the scene at one time or another. At the beginning of World War 11, seven remained; at its conclusion, two. Always before, as some states sank, others rose to take their places. World War I1 broke the pattern; for the first time in a world of sovereign states, bipolarity prevailed. In a 1964 essay, I predicted that bipolarity would last through the century.’ On the brow of the next millennium, we must prepare to bid bipolarity adieu and begin to live without its stark simplicities and comforting symmetry. Already in the fall of 1989, Undersecretary of State Lawrence Eagleburger expressed nostalgia for the ”remarkably stable and predictable atmosphere of the Cold War,“ and in the summer of 1990, John Mearsheimer gave strong reasons for expecting worse days to come.2 For almost half a century it seemed that World War I1 was truly ”the war to end wars” among the great and major powers of the world. The longest peace yet known rested on two pillars: bipolarity and nuclear weapons. During the war, Nicholas Spykman foresaw a postwar international order no different ”from the old,” with international society continuing ”to operate within the same fundamental power pattern^."^ Realists generally shared his Kenneth N. Waltz is Ford Professor of Political Science at the University of California, Berkeley. He has written Man, The State, and War: A Theoretical Analysis f1959), Foreign Policy and Democratic Politics: The American and British Experience (1967, reissued 1992), Theory of International Politics (2979), and numerous essays. His ”Nuclear Myths and Political Realities” won the Heinz Eulau award for best article in the American Political Science Review in 1990. For their thoughtful comments, I should like to thank Karen Adams, David Arase, Jamais Cascio, James Fearon, Robert Gilpin, Robert Keohane, Sean Lynn-Jones, Robert Powell, and Steve Weber. 1. Kenneth N. Waltz, ”The Stability of a Bipolar World,” Daedalus, Vol. 93, No. 3 (Summer 1964). 2. Lawrence Eagleburger, quoted in Thomas Friedman, “U.S. Voicing Fears That Gorbachev Will Divide West,” New York Times, September 16, 1989, pp. 1, 6; John J. Mearsheimer, ”Back to the Future: Instability in Europe After the Cold War,” Znternational Security, Vol. 15, No. 1 (Summer 1990), pp. 5-56. 3. Nicholas J. Spykman, Americu’s Strategy in World Politics: The United States and the Balance of Power (New York: Harcourt, Brace and Company, 1942), p. 461. fnternational Security, Vol. 18, No. 2 (Fall 1993),pp. 44-79 01993by the President and Fellows of Harvard College and the Massachusetts Institute of Technology. 44 The Emerging Structure of International Politics I 45 expectation. The behaviors of states, the patterns of their interactions, and the outcomes their interactions produced had been repeated again and again through the centuries despite profound changes in the internal composition of states. Spykman’s expectations were historically well grounded and in part borne out. States have continued to compete in economic, military, and other ways. The use of force has been threatened, and numerous wars have been fought on the peripheries. Yet, despite deep ideological and other differences, peace prevailed at the center of international politics. Changes in structure, and in the weaponry available to some of the states, have combined to perpetuate a troubled peace.4 As the bipolar era draws to a close, we must ask two questions: What structural changes are in prospect? What effects may they have? The End of Bipolarity-and of the Cold War The conflation of peace and stability is all too common. The occurrence of major wars is often identified with a system’s in~tability.~ Yet systems that survive major wars thereby demonstrate their stability. The multipolar world was highly stable, but all too war-prone. The bipolar world has been highly peaceful, but unfortunately less stable than its predecessor. Almost as soon as their wartime alliance ended, the United States and the Soviet Union found themselves locked in a cold war. In a world of two great powers, each is bound...