After the bipolar world order ended with the Cold War and the collapse of the Soviet Union, what was left, some argued, was a new power distribution within the international system: unipolarity.
Accompanying the new era of unipolarity were questions of its stability and longevity. In 1990 Charles Krauthammer in Foreign Affairs wrote that elements of the “post-Cold War order . . . [make] the coming decades a time of heightened, not diminished, threat of war.” Many consider the United States’ unipolarity simply a “moment” in history, and it will not last. On the other hand, William Wohlforth argues against the emerging portion of scholarly opinion that believes the modern unipolar distribution of power to be both “unstable and conflict prone.” To Wohlforth, the unipolarity of the United States would be a potential decades-long phenomenon, under the premise that the system would be unipolar, peaceful, and durable. However, the argument for the longevity of the unipolar system hinders itself by ignoring the effect of nuclear weapons, the willingness of the unipolar power and the effect of limited conflicts within the system.
Overall, though, the structural approach to thinking about unipolarity disregards the potentially stabilizing effects of nuclear weapons in the international system. Stability – here meaning the lack of great power war, the continuity of the current system with few changes if any – depends on both the structure of the international system as well as the “conscious behavior of the nations that make them up.” Such structures include the theoretical approaches of hegemonic and balance-of-power theory. According to these frameworks, conflict can only occur if the dominant and challenging powers disagree about the magnitude of their own power relative to the others’. However, the power of nuclear weapons seems to change the question of relative power into one of absolute power. In such a sense, neither the unipolar power nor the challenging will have the power to defend or change the status quo, respectively. A relatively weak state with nuclear weapons, for example, complicates the issue, because while the powers may agree about relative power, the absolute power of nuclear weapons may disrupt the balance of power if the state chooses to do so. Thus, using hegemonic theory as an approach to think about the unipolar world’s stability seems to be misguided: while there may be a lack of conflict due to American military power, it is probably not due to the elements of the structure but rather the behavioral ones. Neither the United States nor Russia, the two states with largest nuclear arsenals, would be willing to use nuclear weapons against the other out of fear of creating instability.
Setting aside the willingness of the unipolar power — in this case, the United States — to continue being the unipolar power sets up a major question for the international system: what will happen to the unipolar power if it is no longer willing to be one? U.S officials at the end of the Cold War believed that “any effort to preserve unipolarity was quixotic and dangerous.” Regarding its capabilities, the United States possesses a significantly large latent and military superiority over the next most powerful state.  It appears that within the literature, the argument for unipolar stability resides in the actions of the states that aren’t the unipolar one. Second-tier states should “take no action that could incur [the unipolar power’s] focused enmity.” But such an action seems easier said than done – as a state does not necessarily know the secondary goals of another state, nor does it know the importance of such secondary goals. The lack of clarity of a state’s information hinders the unipolar power’s control in the system. The implied assumption that the unipolar power’s military might ensures it security (and thus survival) thus makes the action of discerning its desires even more difficult, as any such goals would not seem to be with the intention of increasing security. One such example could be that of China and the territorial island disputes in the South China Sea. While China’s actions in the region have caught the eye of the United States, there is the question of how willing the United States is in preventing further action. China has continued to build such islands. The United States, while with more interventionist power, does not seem to be entirely engaging the issue, one thought being that China’s aims are simply not revisionist at all, and thus not a serious concern. The question remains: what preference is the unipolar power willing to engage in conflict over?
The effects of limited conflicts such as civil strife and terrorism contain the ability to affect the stability of the system through the appearance of new actors that are involved in such conflicts. Stability does not have a clear definition in regard to the unipolar world’. Under John Lewis Gaddis’ definition, one such element of stability is the idea of most of the international system’s members remaining. Limited conflict — those not concerning the major powers, which in turn do not represent most of the system — can affect the status of other, minor members. Civil war and terrorism in the Middle East, for example, have the power to change regimes, and ideas of self-determination have led to the creation of new states, such as Kosovo. The approach of analyzing only great power conflicts in history ignores the minor states in the system. If those minor members can emerge and disappear due to limited conflict, then the system, by itself, is not entirely stable.
The unipolar world, at least for the major powers, does seem to be a peaceful one for them. The United States outclasses the world in its military capabilities, thus ensuring both its security and its survival. Focusing solely on the structure of the international system but ignoring the behaviors of states and the minor elements can be misleading. The argument over the longevity of the unipolar system is still up for debate, and it appears that the answer to it will only be met by the passage of time.
 Foreign affairs unipolar moment
 John Lewis Gaddis, “The Long Peace: Elements of Stability in the Postwar International System,” International Security 10, no. 4 (1986), 120
 William C. Wohlforth, “The Stability of a Unipolar World,” International Security 24, no. 1 (1999): 23
 Ibid, 24.
 Ibid., 5
 Ibid., 7
 Nuno P. Monteiro, Theory of Unipolar Politics (New York, NY: Cambridge Univ. Press, 2014), 134.