Articles

Two factors determine whether China makes major changes in military strategy: shifts in the international conduct of warfare and unity of the Chinese Communist Party leadership.

The defining question about global order for this generation is whether China and the United States can escape Thucydides’s Trap. The Greek historian’s metaphor reminds us of the attendant dangers when a rising power rivals a ruling power—as Athens challenged Sparta in ancient Greece, or as Germany did Britain a century ago. Most such contests have ended badly, often for both nations, a team of mine at the Harvard Belfer Center for Science and International Affairs has concluded after analyzing the historical record. In 12 of 16 cases over the past 500 years, the result was war. When the parties avoided war, it required huge, painful adjustments in attitudes and actions on the part not just of the challenger but also the challenged.

"In our view, the field has moved away from a careful reliance on theory, and is just mindlessly going out and testing hypotheses without thinking very hard about what's really causing what."

"The conventional wisdom among those who looked at the Middle East used to be that you had a choice either of supporting the autocrat or being stuck with the religious extremists. The extraordinary diffusion of information created in Egypt and other Middle Eastern countries reveals a strong middle that we weren't fully aware of. What is more, new technologies allow this new middle to coordinate in ways unseen before Twitter, Facebook, and so forth, and this could lead to a very different politics of the Middle East. This introduces a new complexity to our government's dealings with the region."

States use wedge strategies to prevent hostile alliances from forming or to dis­perse those that have formed. These strategies can cause power alignments that are otherwise unlikely to occur, and thus have significant consequences for international politics. How do such strategies work and what conditions promote their success? The wedge strategies that are likely to have significant effects use selective accommodation—concessions, compensations, and other inducements—to detach and neutralize potential adversaries. These kinds of strategies play important roles in the statecraft of both defensive and offensive powers. Defenders use selective accommodation to balance against a primary threat by neutralizing lesser ones that might ally with it. Expansionists use se­lective accommodation to prevent or break up blocking coalitions, isolating opposing states by inducing potential balancers to buck-pass, bandwagon, or hide. Two cases—Great Britain’s defensive attempts to accommodate Italy in the late 1930s and Germany’s offensive efforts to accommodate the Soviet Union in 1939—help to demonstrate these arguments. By paying attention to these dynamics, international relations scholars can better understand how balancing works in specific cases, how it manifests more broadly in interna­tional politics, and why it sometimes fails in situations where it ought to work well.

There is broad scholarly consensus that the relative power of the United States is declining and that this decline will have negative consequences for interna­tional politics. This pessimism is justified by the belief that great powers have few options to deal with acute relative decline. Retrenchment is seen as a haz­ardous policy that demoralizes allies and encourages external predation. Faced with shrinking means, great powers are thought to have few options to stave off decline short of preventive war. Contrary to the conventional wis­dom, however, retrenchment is not a relatively rare and ineffective policy in­strument. A comparison of eighteen cases of acute relative decline since 1870 demonstrates that great powers frequently engage in retrenchment and that re­trenchment is often effective. In addition, we find that prevailing explanations overstate the importance of democracies, bureaucracies, and interest groups in inhibiting retrenchment. In fact, the rate of decline can account for both the ex­tent and form of retrenchment, even over short periods. These arguments have important implications for power transition theories and the rise of China.