In an interesting article at the Foreign Policy website and entitled "The World War Inside Islam," James Traub asks whether there’s a central American role in the struggle against violent Islamist extremism. His answer is delivered in the subtitle: "Why the United States can do very little to alter the course of events in the Middle East right now."
Traub is right in suggesting that "the locus of that struggle is shifting from the West to the Islamic world itself" but then goes on to say that "the West can defend itself, but there’s little it can do to change the terms of that struggle."
Here I think he is missing a key element. He describes the many ways in which Western efforts have failed and/or will fail, and the analysis is sharp: I share his dim view of Obama policy (or non-policy) in Syria. But he does not take full account of the importance of success, or momentum. Surely one of the reasons ISIS is attracting recruits is that it appeared to be winning, going from victory to victory. Potential recruits will naturally want to join such a group instead of its less successful rivals, and may even be persuaded that it is winning because God is on its side.
Here the United States role can be central: stop ISIS from having all these victories. Stop the momentum. Erode the image of success. Traub is not against a military role for the United States, but I think he underestimates the utility of making ISIS a failure. Easier said than done, to be sure, but the rate at which ISIS is conquering territory has changed already, and air power can achieve a great deal against the group.
Traub insightfully discusses the legitimacy and illegitimacy of Arab regimes, ISIS’s ideological and religious appeal, and other aspects of the struggle that may be even more important than the "merely" military side. But ISIS did not gain all that territory and a surge of recruits from around the globe just because of ideology or because its opponents are sometimes regimes whose popularity and legitimacy are questionable. Victory breeds the sense of inevitable future victory--momentum. Defeat, retreat, setbacks, casualties will have an opposite effect. It’s hard to see that happening without leadership from Washington, ranging from military aid and training, to diplomatic efforts to create and lead coalitions, to actual use of American air power and some troops on the ground. ISIS will not be defeated "merely" by battlefield successes, but it won’t be defeated without them.