Over and done with. That might seem impossible in the face of ISIS, terrorism, Iranian ballistic missiles, and other US security interests, but a military withdrawal from the Middle East is by far the safest path for the United States and the region. That approach has instructive historical precedents.

America has been no different from other imperial powers in finding itself ensnared repeatedly in costly, bloody, and eventually futile overseas wars. From the Roman empire till today, the issue is not whether an imperial army can defeat a local one. It usually can, just as the United States did quickly in Afghanistan in 2001 and Iraq in 2003. The issue is whether it gains anything by doing so. Following such a "victory," the imperial power faces unending heavy costs in terms of policing, political instability, guerilla war, and terrorist blowback.