Unipolarity is unsustainable and not peaceful.

It is not that the core of Wohlforth' s widely shared argument is wrong, how- ever: great power conflict is impossible in a unipolar world. Rather, his claim that unipolarity is peaceful has two important limitations. First, it focuses on great powers. But because unipolarity prevents the aggregation of conflicts in- volving major and minor powers into conflict between great powers, scholars must look beyond great power interactions when analyzing the structural incentives for war. Second, Wohlforth assumes that the unipole' s only reason- able strategic option is defensive dominance. But given that unipolarity pro- vides the unipole with ample room for defining its foreign policy, offensive dominance and disengagement are equally plausible strategies. This requires a look at how these two additional strategies facilitate conflict.

After correcting for these two limitations, it becomes clear that unipolarity possesses much potential for conflict. Contrary to what Wohlforth argued, unipolarity is not a system in which the unipole is spared from any conflicts and major powers become involved only in peripheral wars. Instead, a unipo- lar system is one that provides incentives for recurrent wars between the sole great power and recalcitrant minor powers, as well as occasional wars among major and minor powers. That is the central prediction of my theory. To be sure, the unique historical character of the current unipolar era makes the task of building a general theory of unipolarity difficult. Particularly, it re- quires great care in distinguishing between those features of the post-Cold War world that are intrinsic to a unipolar system and those that stem from specific aspects of contemporary international politics. Two points deserve mention.

First, my theory of conflict in unipolarity is robust to changes in military technology. Still, some such changes would mean the end of unipolarity. At one end of the scale, some scholars argue that the widespread possession of equalizing technologies such as nuclear weapons would turn all minor powers into major powers and decrease the use of the unipole' s power-projection ca- pabilities in ways that might invalidate the label of unipolarity.113 At the other end of the scale, should the unipole develop a splendid first-strike capability against all other states - an unlikely prospect, no doubt - its relative power would increase, perhaps replacing anarchy with hegemony.114 Both of these developments would mean that my theory no longer applies.

Second, my argument is robust to changes in the geographical configuration of the distribution of power. Were a future unipolar era to feature a continen- tal, rather than an offshore, unipole, the paths to conflict described above would still apply. A continental unipole's inability to disengage from its neigh- bors might increase the proportion of conflict in which it will be involved at the expense of conflicts between others, but the conflict-producing mecha- nisms would remain the same.115

From the perspective of the overall peacefulness of the international system, then, no U.S. grand strategy is, as in the Goldilocks tale, "just right/'116 In fact, each strategic option available to the unipole produces significant conflict. Whereas offensive and defensive dominance will entangle it in wars against recalcitrant minor powers, disengagement will produce regional wars among minor and major powers. Regardless of U.S. strategy, conflict will abound. In- deed, if my argument is correct, the significant level of conflict the world has experienced over the last two decades will continue for as long as U.S. power remains preponderant.