Enduring rivalries are crucial topics in world politics. From both theoretical and policy perspectives, it is important to know when a rivalry begins and when it ends, and more significantly, why only a few rivalries end up as enduring, in terms of their duration, intensity, and societal as well as international impact. We now have a corpus of literature on enduring rivalries, especially the reasons for their longevity. Less known are the reasons why some enduring rivalries end, sometimes peacefully or following a crisis or a war.

The book under review makes a compelling effort to identify the conditions associated with rivalry termination. Coauthored by two scholars who have dealt with the subject for a long time (Karen Rasler and William R. Thompson) and a South Asia scholar with expertise on the region (Sumit Ganguly), How Rivalries End offers a fruitful combination of theory and case studies.

The model the book presents replicates five key interlinked factors already known in the literature as vital for rivalry termination: external or internal shocks, expectational revisions, reciprocity, and reinforcement. If these conditions emerge in a rivalry one by one in a positive manner, a long-standing rivalry could end. Critical turning points are crucial as these offer windows of opportunity when decision makers recognize that conflict resolution strategies have a possibility for success. Expectational revisions are generated by political shocks when elites question the viability of existing strategies. Shocks can also give rise to new decision makers who hold different expectations and strategies. If proper negotiations are held following power shifts or strategy changes while leaders communicate their intentions clearly and convincingly, reciprocal reinforcement and conciliations can take place. Third parties can also play a significant role in some cases as mediators or through their strategy of carrots and sticks.

It should be noted that this process need not be linear or without upsetting events in between. An interesting dimension is that even when some shocks generate negotiations, spoilers of peace could derail the process. Take the case of the India–Pakistan peace process. During the past 66 years of this rivalry, leaders were on several occasions close to reaching major agreements, yet failed to pull it off. The Pakistani military taking the offensive in the Kargil crisis derailed the Lahore peace process between Prime Ministers Atal Bihari Vajpayee and Nawaz Sharif in 1999. Nonstate actor behavior, as in the cases of the terrorist strikes on the Indian Parliament in 2001 and the Mumbai attacks in 2008, all indicate that state elites may have noble intentions, but some of the countervailing power centers do not necessarily share those objectives. Indeed, a key challenge to ending persisting rivalries, such as in the cases of India–Pakistan and Israel-Palestine, is the unwillingness of state leaders to overcome the hurdles generated by spoilers of peace. Although a top-down approach is useful for terminating rivalries, the role of substate actors should be incorporated in some fashion to show that state elites are not the only players that matter and that they need not be a unified force regarding rivalry termination. It is crucial to know why some leaders are more successful in taming the spoilers than others. A path-dependent approach by the authors would have been useful for seeing variations in the outcomes.

Ten rivalries are examined more closely in the case study section: Egypt–Israel, Israel–Syria, Palestine–Israel, India–Pakistan, China–United States, China–Soviet Union, China–Taiwan, China–Vietnam, Thailand–Vietnam and North Korea–South Korea. Four of them were terminated permanently, three cases produced serious de-escalations, and three have been lingering without resolution. Within the cases, 33 subcases of de-escalation efforts are discussed. These case studies offer a significant milieu for understanding the deep currents flowing in a rivalry relationship that often generate outcomes that parties did not expect beforehand. Some of these cases occurred in an interdependent context of a regional subsystem, and hence the analysis takes a macro-level approach.

The book discusses a number of pathways by which rivalries end: a) One or both parties lose their competitive edge through decisive defeats with or without war; b) one side or both sides experience political exhaustion or intense civil war; and c) one or both are perceived as no longer threatening by the other. The latter can happen when shifts take place in the strategic priorities of the elite, changes occur in domestic leadership, regimes are altered, and successful mutual negotiations take place. Among the general category of rivalries between 1816 and 2010, one side was coerced to surrender in 48 cases, while 76 gave up rivalry noncoercively. In addition, 15 were the result of acknowledgment of inferiority by one side.

Chapter 8 synthesizes the findings and concludes with significant support for the model. The findings suggest that for rivalry termination to occur, macro conditions need not fully converge or policy entrepreneurs emerge, nor are external actors needed in all cases. There are also variations among Eurasian, sub-Saharan, and Latin American cases.

One weakness of the book is the mixing of different rivalries without properly categorizing them. As is well known, great-power rivalries are different in many respects from small- or middle-power rivalries. Great powers tend to have competition over power and status, variables that may not be replicable in the contexts of non-great-power states. It would have been useful to categorize the different kinds of rivalries based on the power capabilities of states. For example, it might be beneficial to look at great-power rivalries, middle-power rivalries, great-power/small-power rivalries, and the like. It is all the more interesting to see how a small state can sustain a rivalry with a great power for a long period of time. The examples of United States–Iran, United States–Cuba, and United States–Venezuela indicate that material power is not sufficient to explain rivalry persistence. Even great-power regional rivalries can assume different forms. It is interesting to analyze why the Sino–Indian rivalry is different from the India–Pakistan rivalry. The book does not mention the Sino–Indian rivalry at all. This is perplexing, since this has been one of the leading rivalries of Asia and will likely be continuing for several decades to come for various systemic and status reasons.

The combination of deductive and case study methods adopted by Rasler, Thompson, and Ganguly is interesting. However, a careful discussion of the reasons these cases were chosen and not others would have been beneficial. The authors, to their credit, offer an appendix summarizing other works on rivalry termination. But a clearer delineation of these approaches from this work would have been fruitful. The authors also point out that rivalries are becoming less common in contemporary world politics. This itself calls for an investigation. Might this be because as the state system gets settled among newly emerging states, the opportunity for rivalry also has declined? Does a major systemic transformation like the end of the Cold War have anything to do with this phenomenon? How about the intensified globalization and the increasing economic interdependence generating fewer incentives for big rivalries to spring up? We do not get a sense from reading this book that systemic factors, in particular great-power support for rivals, play any significant role in the persistence and/or termination of rivalries. Economic calculations are also given little significance in the discussions. The macro-level processes in the world system are perhaps overlooked in assessing the microprocesses, especially at the decision-making level, as causal explanations for rivalry terminations.

Overall, this is a good book with a modest theoretical argument and some interesting case study materials. It is a fine addition to the literature on enduring rivalries, in particular the microfoundations of rivalry terminations and the key factors that promote or impede resolutions to unending conflicts. Much work is needed to explore the relationship between macro- and micro-level factors. Additional empirical studies are also needed on neglected cases of rivalry termination in order to get a full handle on the phenomenon.