Gabriella Blum's book is built on the assertion that some conflicts cannot be resolved. She argues that since some conflicts will always be inescapable, the academic approach should move away from conflict prevention and resolution to the broader and more accurate notion of conflict “management.” Blum argues that considering conflicts as one whole phenomenon, or as a total relationship, leads scholars to search for one big (and often simplistic) solution for their resolution. She maintains that interstate relations are multidimensional and that conflicts should be seen as only one aspect of interstate relations. She asserts that “by concentrating our efforts … on conflict resolution only, we often neglect the potential of reinforcing those elements that fall outside the conflict yet inside the relationship” (p. 5).

These nonconflictual elements represent potential zones of interstate cooperation, which are referred to in the book as “islands of agreement.” These zones of agreement can generate “regimes of joint venture, in which parties realize mutual gains from reciprocal or interdependent efforts” (p. 21). Blum claims that interstate regimes can manage enduring interstate rivalries by rendering certain aspects of a dyadic relation impermeable from a zone of conflict. She attempts to understand how international regimes (i.e., zones of cooperation) are “formed, what makes them sustainable, and what their potential impact on the relationship might be” (p. 5).

To this extent, Blum's research puzzle has already been partly addressed in the literature on international regimes. In the last 25 years, scholars of international relations have been interested in studying why interstate cooperation occurs, how it is sustained, and why it fails. When addressing the issue of cooperation, scholars have focused their attention on how formal and informal international regimes are created and how they impact interstate relations. For example, in 1983, Stephen D. Krasner edited International Regimes, in which he defined regimes as “sets of implicit or explicit principles, norms, rules, and decision-making procedures around which actors' expectations converge in a given area of international relations” (Krasner, p. 2). The impact of regimes on international relations has been studied by numerous liberal and realist scholars, and a rich body of literature exists on this topic. Thus, Blum's book is an interesting conceptual and empirical contribution to the burgeoning literature on interstate regimes and cooperation. However, she does not directly address this literature and does not indicate where her book stands in the current academic discussion on international regimes.

Islands of Agreement provides rich empirical information on some of the most important protracted conflicts since 1945. It is well organized, and the logic of Blum's argument is straightforward. The book performs an inductive analysis of three important protracted conflicts (India-Pakistan, Greece-Turkey, and Israel-Lebanon), where rivals have been able, with differing levels of success, to develop islands of agreement outside the zones of conflict. The analysis raises some interesting criteria that must be present for the creation and endurance of the islands of agreement. She indicates, among other things, that cooperation can occur if political issues are “divisible,” that is to say, if some aspects of interstate cooperation can remain “dry” from enduring rivalry and conflict. Moreover, there must be relative parity in the cost and benefit equation of interstate cooperation, that is to say, that identical constraints must be imposed upon the two rivals. Otherwise, islands of cooperation will not develop, or if they do, they will not endure. Blum also points out that formal and institutionalized regimes of cooperation provide better and more sustainable cooperation than informal ones. These findings are valuable to the extent that they give an indication of what makes interstate cooperation sustainable.

The author's research method offers conclusions that are difficult to generalize to the whole universe of cases, however. The book delineates an interesting and imaginative conceptual framework, but it lacks a theoretical argument of conflict management necessary to prescribe solutions and predict the occurrence of sustained zones of cooperation. Indeed, how can Blum's framework be tested and refuted if it is not theoretically grounded? She describes interstate cooperation in detail, and derives inductive conclusions by identifying patterns, similarities, and differences among the three cases studied. But the analysis does not retrace the causal mechanisms that lead states to either cooperate or not, and there is no theoretical connection between the existence of a cooperative space and the successful management of a zone of conflict. What happens when cooperation between two rivals is quasi-nonexistent? Does it necessarily mean that the conflict would not be manageable? Can self-constrained decisions made by governments experiencing an interstate conflict play a role in the management of the conflict? In other words, is cooperation always accountable for conflict management, or may other factors such as domestic politics considerations interfere in the decision-making process? Blum argues that islands of agreement can develop between states and reduce the perverse effects of conflict, but she does not really explain how these zones of cooperation can develop nor what leads states to create them. Her book would have clearly benefited from a deductive theoretical framework, which could have driven the whole empirical analysis. Moreover, specified hypotheses would have substantially improved the nature of the research.

One important question arises: Does Blum's shift in perspective provide better explanations of the complex phenomenon of interstate conflicts and cooperation than the more traditional literature on conflict prevention and resolution written by scholars like Clifton Morgan, Edward Azar, or William Zartman? Considering that the book makes no theoretical breakthrough to this effect, the answer is no. Furthermore, Blum's premise that some conflicts are inescapable is very much debatable. Such a statement does not seem to be grounded in long-term empirical evidence. The three dyadic conflicts that she studies have lasted for less than 60 years, and although they appear intractable, it is hasty to conclude that they are irresolvable. The recent resolution of the conflict in Northern Ireland reinforces this point.

In addition, it is not clear how islands of agreement connect to a potential for managing protracted conflicts. In fact, it seems that these islands consist of a line of communication between rivals and manage the zones that are not affected by the conflict. Therefore, what real impact can these islands have on the zone of conflict?

Despite these flaws, Islands of Agreement has the merit to propose a new angle of research for the study of protracted armed conflicts. This is a significant conceptual contribution. The book is valuable, since it forces the reader to think outside the box and provides important information on the cooperative side of some of the most enduring interstate rivalries.