In light of the deep involvement of the United States in occupation and nation building in Afghanistan and Iraq after the events of September 11, 2001, the question of when and under what conditions military occupations succeed or fail is now at the top of the U.S. foreign policy agenda. The Bush administration took the country to war in each case with the assumption that the postwar occupations of these two countries would not be long-lasting or problematic. This assumption was, in turn, based upon a cursory reading of two cases of successful occupation—Germany and Japan after World War II. Given that neither post-9/11 occupation has proven entirely satisfactory, the time is ripe for a systematic investigation of the factors that lead to the success or failure of military occupations. David Edelstein's fine book unfortunately comes too late to have prevented American policymakers from making numerous missteps, but it will at least help them understand exactly where they went wrong and hopefully lead them to think more clearly and systematically about future military occupations.

After surveying the universe of cases of military occupations since 1815, Edelstein concludes that only seven out of 26–27%—were successful. He attributes the difficulty of undertaking successful occupations to two important phenomena: First, because of the rise of nationalism in the last two hundred years, most people simply do not have much tolerance for foreign troops in their country. Second, because most areas of the world are not of much material value to occupying powers, public support in them for a long-term and costly occupation often flags very quickly. Given these two factors, it is not surprising that most occupations fail.

Edelstein also offers an elegant and convincing theory to explain when occupations succeed. He argues that the resistance of the host population and the apathy of the occupying state's population can be overcome when there is recognition of a common external threat. This threat minimizes nationalism in the host country by making the occupier seem like the “lesser evil,” which in turn makes it possible for the occupying power to employ cooperative, rather than coercive, measures to sustain its presence. The threat also raises the stakes for the occupying power in a successful occupation, and so also bolsters public support for staying the course. This theory nicely accounts for the successes that the United States enjoyed in Germany and Japan at the beginning of the Cold War and also helps us understand why other occupations have not gone so well.

Edelstein also does a convincing job of laying out and critiquing the most likely alternative explanations for the success or failure of military occupations. The most common of these is that success or failure depends simply upon a sufficient investment of time and resources by the occupying power. This argument is, of course, nearly tautological, and there are many instances of occupying powers making significant investments of blood and treasure yet still failing, as seems to be the case in Kosovo. Another alternative argument is that success or failure depends upon the level of economic development of the occupied territory. But as Edelstein persuasively argues, occupying powers only allow occupied states to develop when they sense a common threat. Finally, many believe that since unilateral occupation is illegitimate in both the host and occupying countries, only multilateral occupations have sufficient legitimacy to dampen host country nationalism and sustain occupying country resolve. Edelstein concedes that there is something to this last argument, but shows that even multilateral occupations still depend upon a common threat for success.

In the interest of pushing the debate further, however, let me suggest one area where I think Edelstein could have done more in terms of his argument. Specifically, the notion of “threat” is not as well developed as it could be. There are two important issues here.

First, threats are not always self-evident. Indeed, even realist theorists acknowledge that threats are functions of both an adversary's capabilities and its intentions, and the latter are hard to divine and can in any case change quickly. Given that, threat assessment is by no means straightforward. Indeed, one does not have to be a social constructivist to suggest that threat manipulation is a possible strategy for occupying powers, toward both the occupied and their own publics.

Second, Edelstein's discussion of threats focuses mostly on their external manifestation—does another country present a common threat to both the occupier and occupied?—and devotes less attention to internal threats within the occupied country itself. To the extent that he touches on them, he focuses mostly on threats from the occupied to the occupiers. But as the case of Iraq illustrates quite clearly, the occupied are often not monolithic, and factions can present threats to each other (Sunni vs. Shia) and can form links with external powers (Iraqi Shia and Iranian Shia). My read of the so-called Anbar awakening—one of the keys to the recent decline in Sunni resistance to the U.S. occupation in Iraq over the last year—is that it was the result not so much of the “surge” of additional U.S. ground forces but, rather, of the belated realization by the Sunnis that they now face a government dominated by the Shia majority bent on asserting their hegemony and exacting retribution for past Sunni crimes.

If one accepts this account of what is transpiring in Iraq, it seems to me that further conceptual, empirical, and policy research building on Edelstein's work would have to recognize that there is an element of subjectivity in threat assessment that cannot be ignored. Additionally, many of the states we have occupied, or are likely to occupy in the future, have deep internal cleavages, and the threat relationships among factions of the occupied present theoretical puzzles we need to unravel, as well as policy pitfalls and opportunities that occupiers need to understand.

Still and all, Occupational Hazards is one of those rare books that seamlessly blends theory, historical case studies, and policy relevance. For all of those reasons, this is a very good book, and I am confident that other scholars will read it with interest. I really hope that it also attracts the attention it deserves from among U.S. policymakers. They are less likely to read it because few read scholarly books, but policymakers are the ones who most need to do so before they embark on future military occupations.