There is no regional military force capable of defeating ISIS: The solution to ISIS is not a military one. Still, military force could stop ISIS gains and begin to lay the basis for the group’s demise. But there is no force, nor combination of forces, willing or able to accomplish this objective. The notion of an Arab state coalition will remain a thought experiment, and the Iraqi military, as seen recently in Ramadi, is not up to the job. Political considerations – largely Shiite pushback – prevent the training and arming of Sunni tribes and militias. The Kurds are too weak, and their peshmerga too localized a force. Even Iran’s Shiite militias would have a hard time defeating the Islamic State in Sunni-majority areas, and relying on Iran would threaten the already precarious balance between Sunni and Shiite Iraqis. A fully effective Iraqi national army, with the will and the capacity not just to retake territory but to hold it, would be the answer – but that for now seems a distant dream.

The United States lacks the will for this fight: Americans could defeat the Islamic State on the battlefield – certainly in Iraq, and probably in Syria, too. But the odds of this administration, or even one led by a Republican successor, being willing to make the necessary commitment to both battlefields, seem very small indeed. The American public and the U.S. Congress have grown risk-averse after years of investment in the Middle East that brought no tangible returns. Moreover, at times military force is simply an instrument to achieve sustainable political goals. There is simply no reason to believe that the political end state in Iraq or Syria would turn out any better than it did in Iraq or Afghanistan over the past decade, when the United States deployed tens of thousands of troops and spent trillions of dollars.