Foreign policy difficulties usually produce extensive scholarship. Vietnam led to numerous appraisals and reappraisals, many of which paralleled the protests in being heartfelt and radical. Perhaps because of the lack of a draft, Iraq's protests have been cooler and more muted, and the scholarship has tended to be more analytical and mainstream. James Lebovic's excellent study looks at both cases to drive home the argument that was part of the Vietnam critique: Even if the United States is the most powerful state in the international system, there are sharp limits to what it can accomplish, and its very power creates some of those limits (see William J. Fulbright, The Arrogance of Power, 1966)

The two cases are very different, but they reveal parallel hurdles that the United States was unable to surmount. Lebovic groups them under four headings: the military difficulties in fighting a guerrilla war in a foreign country, the related problems of halting outside support for the rebels and winning over the population, the asymmetry between the strength of the American commitment and that of its adversaries, and the exasperating experience of dealing with the host government. None of this is entirely unfamiliar, but it is argued with depth and subtlety, and those who urged the invasion of Iraq would have been well advised to think about these problems ahead of time.

Let me first summarize the argument and then turn to criticisms. What is crucial is that America's overwhelming military strength does not automatically translate into the ability to defeat unconventional forces fighting on familiar physical and human terrain who are highly motivated and have extensive popular support. And, of course, one reason why adversaries fight in this way is that the United States has overwhelming conventional superiority. Unconventional wars share with many exercises of power the annoying fact that the outcome depends not only on what the United States does but also on the choices of third parties, the American public, those the United States is trying to help, and, most of all, the adversaries. It is then a question of what leverage the U.S. has over them, and what leverage they have over the United States. In Iraq, furthermore, American ideology led it to define victory as the establishment of a liberal democracy, a goal that was beyond the reach not only of American military might but also of anyone's capabilities for social engineering.

Lebovic's analysis of the military problems of coping with an insurgency is well done if familiar, and he departs from conventional popular wisdom by noting that the best analyses show that the current incarnation of counterinsurgency (COIN) is far from a panacea and that the success of the “surge” in Iraq depended on far more than an increase in American troops and a change in doctrine. The decisions by the Shi'a leader Moqtada al Sadr and the desire of many Sunni to change their tactics (the “awakening movement”) were crucial; the American role was largely limited to taking advantage of these opportunities, and the resulting relative calm may not be permanent. Furthermore, and a point that Lebovic could have stressed more, there is a fundamental tension if not contradiction at COIN's heart: On the one hand, it recognizes that foreign forces generate local resistance, but it also argues that persistent presence is required to guarantee continued security to those willing to support the government (the most eloquent argument for both of these conflicting insights is David Kilcullen, The Accidental Guerrilla: Fighting Small Wars in the Midst of a Big One, 2009). Relatedly, as the newspaper stories from Iraq and Afghanistan make clear, the use of force can create more insurgents than it kills (pp. 32–57), and as current controversies in Afghanistan show, there are understandable limits to the military's willingness to sacrifice American lives by restraining its firepower.

If counterinsurgency presents a military asymmetry, the nature of these wars, and of many other conflicts, shows a crucial political asymmetry. Following Andrew Mack's pathbreaking article “Why Big Nations Lose Small Wars: The Politics of Asymmetric Conflict” (World Politics 27 [January 1975]: 175–200), Lebovic argues that while the United States is motivated enough to enter these wars, its interests, and therefore the intensity of its preferences, are much less than those of the adversary, giving the latter a great bargaining advantage (see Alexander George, David K. Hall, and William E. Simons, The Limits of Coercive Diplomacy, 1971). Thus, while the American forces were able to inflict much higher casualties on their Vietnamese adversaries than they were able to inflict on the United States, the North could and did refuse to relent. This asymmetry in strength of motivation was not understood by a wide range of American decision makers, who assumed that the overwhelming military power of the United States would enable it to prevail. In Iraq, things are more complex, but the very fact that the insurgents fought so long and hard meant that even if they did lose, in a real sense the United States did so as well, in that the costs it paid were much higher than expected, the hope to quickly establish a friendly and democratic regime was thwarted, and the war became a recruiting poster for terrorism.

In Iraq, the United States faced not only an insurgency but also a civil war. Lebovic, of course, knows this but might have placed a bit more stress on two points. First, while the outside intervener may have a highly motivated local ally, unless it wants to see the ally's rivals crushed, it will have a very delicate balancing act. Combining the difficulties facing peacekeepers—or rather peacemakers—and counterinsurgents, the United States sought to isolate Al Qaeda and other “hard-core” resisters, but also had to bring all other factions to the table. Military force is not irrelevant here because the local actors are more willing to bargain when they see that military victory is impossible, but it is far from sufficient. Indeed, the whole language of victory is inappropriate, or at least needs to be redefined: The United States wanted to end, not to win, the civil war. A second crucial implication of the fact that Iraq was in a civil war is that America's Shi'a allies could do things that the United States could not. In a throwback to the tactics that imperialist powers adopted in the previous century, Shi'a factions murdered, tortured, and terrorized their Sunni opponents. Although we hate to admit it, this produced effects that were beneficial to the U.S. war strategy, at least in the short run. The Shi'a and Sunni populations segregated themselves, thus reducing the local security dilemmas, and it appears that many Sunni came to realize that they were indeed a minority in the country and could not win the civil war.

The final problem and crowning insult facing the United States and other interveners is that great material power does not produce influence over local clients. In Vietnam, the United States strenuously pressed the government to broaden the base of its support (e.g., through the land reform), to become more efficient (e.g., by limiting corruption and promoting military commanders on the basis of ability rather than loyalty to the leader), and to fully mobilize the society. But this did not work, even after the United States had flexed its muscles by collaborating in the overthrow of the original South Vietnamese leader, Ngo Dinh Diem. The essential problem is what Douglas Macdonald (Adventures in Chaos: American Intervention in the Third World, 1992) called the “commitment trap”: The United States can make demands, establish conditions for further aid, and carp, but threats to withdraw if the client does not reform are not credible because once the United States intervenes, it cannot readily leave. In the end, of course, the Americans did withdraw from Vietnam and will do so from Iraq, and once it becomes clear that this is happening, the local actors have incentives to take measures that the United States wanted but had been unable to extract before (although they also have incentives to do things that the United States does not want). As Lebovic shows, the dynamic was particularly interesting in Iraq, where the need to negotiate a status-of-forces agreement gave Prime Minister Nouri al-Maliki a bargaining advantage that he used to set deadlines for the American withdrawal, something the Bush administration had resisted. In a further irony, it was the limited but not trivial American military success that enabled Maliki to pursue this objective.

Overall, this is an excellent study. Passionate in its conception but analytical in its execution, it shows in rich detail the barriers to translating military might into political victories. But, of course, it is open to objections. Defenders of these wars would argue that, costly as they were, the failure to fulfill all American goals should not blind us to what they did gain in Vietnam and Iraq. Space limitations prevent me from spelling out these claims, but any of us who have debated these issues will be familiar with them. The essential point is that the focus on the limits of military power may obscure what it can do.

A second objection is that Lebovic has loaded the deck by selecting these cases. They loom so large to us for the very reason that they are costly and partial, if not complete, failures. But the threat and use of force often does work, and when it does the cases trouble us less as citizens and scholars, and we study them less, if not let them slip from sight. Force worked in the Gulf War and in the interventions in Panama, the Balkans, and in Haiti (cases Lebovic touches on pp. 224–25). Though beyond the scope of Lebovic's study, a comparison among these cases would be useful, even beyond the obvious point that size matters.

A related question is whether the failures were the result of inherent limitations or bad policies. Knowing what we now know, could the United States have won in Vietnam and/or Iraq? The latter case looks more promising than the former, and the obvious counterfactual is that the United States would have used a much larger force, planned for the occupation, constructed a more careful de-Baathification policy, and reached out to Iraq's neighbors. Lebovic notes this question (pp. 178–79, 203, 207), but further discussion, though necessarily speculative, would have been valuable.

A final point, as much an extension of Lebovic's argument as an objection to it, is that we need to further explore why the United States felt the need to intervene. Although this topic is beyond the scope of his book, it intersects with it in at least two points. First, the irony is that the very extent of American military power creates the temptation to use it (which is why some analysts call for radical cuts to the military budget; see Christopher Preble, Power Problems: How American Military Dominance Makes Us Less Safe, Less Prosperous, and Less Free, 2009), and that military successes will lead powerful states to undertake even more ambitious missions. The limits of military power are revealed only when the state bumps into them. The United States might not have intervened in Iraq had Afghanistan not appeared to have been a success; had Iraq proved as easy as the Bush administration expected, the United States might have moved on to Iran. Second, although Lebovic is correct to stress the motivational asymmetries that are so damaging to American leverage, the American worldwide commitments that both generated and were generated by its military superiority are what led to such a heavy investment of resources and prestige in the conflicts. The main reason the Americans fought in Vietnam despite the knowledge that the war would be difficult and the prospects uncertain was the belief that allowing the country to “fall to communism” would have deleterious effects around the world. Bush overthrew Saddam in large part because he saw threats and opportunities to important American global interests. In other words, what was at stake for America leaders extended far beyond the particular country they were fighting in, and this produced quite a bit of staying power.

Lebovic stresses that the United States has such dispersed interests that it cannot fully mobilize for conflicts like these. He is correct, but it is the very widespread nature of these interests that drives American behavior. Unfortunately, the result is a motivation strong enough to produce these entanglements but not so strong as to permit it to prevail in them.