Sage advice for Obama from a 2007 report from the Brookings Institution: “the only things standing between Iraq and a descent into a Lebanon- or Bosnia-style maelstrom is 140,000 American troops.”

And if the future of Iraq is not sufficient motivation, there’s the legacy: If America withdraws, “we should expect many hundreds of thousands or even millions of people to die with three or four times that number wounded . . . . Of course, an Iraqi civil war will be even more painful for Americans to bear because, if it happens, it will be our fault. We will have launched the invasion and then failed to secure the peace, a failure that will have produced a civil war. For years to come Iraqis, Americans, and indeed most of the world will point their fingers at the U.S. government.”