ABSTRACT
The collapse of the Soviet Union produced the greatest change in world power relationships since World War II. With Moscow's headlong fall from superpower status, the bipolar structure that had shaped the security policies of the major powers for nearly half a century vanished, and the United States emerged as the sole surviving superpower. Commentators were quick to recognize that a new "unipolar moment" of unprecedented u.s. power had arrived.1 In 1992 the Pentagon drafted a new grand strategy designed to preserve unipolarity by preventing the emergence of a global rival.2 But the draft plan soon ran into controversy, as commentators at home and abroad argued that any effort to preserve unipolarity was quixotic and dangerous.3 Officials quickly backed away from the idea and now eschew the language of primacy or predominance, speaking instead of the United States as a "leader" or the "indispensable nation.,,4
The rise and sudden demise of an official strategy for preserving primacy lends credence to the widespread belief that unipolarity is dangerous and unstable. While scholars frequently discuss unipolarity, their focus is always on its demise. For neorealists, unipolarity is the least stable of all structures because any great concentration of power threatens other states and causes them to take action to restore a balance.s Other scholars grant that a large
concentration of power works for peace, but they doubt that U.S. preerriinence can endure.6 Underlying both views is the belief that U.S. preponderance is fragile and easily negated by the actions of other states. As a result, most analysts argue that unipolarity is an "illusion," a "moment" that "will not last long," or is already "giving way to multipolarity.,,7 Indeed, some scholars question whether the system is unipolar at all, arguing instead that it is, in Samuel Huntington's phrase, "uni-multipolar."s
Although they disagree vigorously on virtually every other aspect of postCold War world politics, scholars of international relations increasingly share this conventional wisdom about unipolarity. Whether they think that the current structure is on the verge of shifting away from unipolarity or that it has already done so, scholars believe that it is prone to conflict as other states seek to create a counterpoise to the overweening power of the leading state. The assumption that unipolarity is unstable has framed the wide-ranging debate over the nature of post-Cold War world politics. Since 1991 one of the central questions in dispute has been how to explain continued cooperation and the absence of old-style balance-of-power politics despite major shifts in the distribution of power.9
