In June 2014, the Sunni militant group ISIS declared that it had established a new caliphate spanning territory in Syria and Iraq. Since then, the region under its control has expanded, despite airstrikes and the deployment of U.S. military advisers, and Jihadist groups across the Muslim world have pledged their allegiance. What should the Obama administration's next steps be? Should the U.S. goal be containment, or can ISIS be defeated? For the motion: Philip Zelikow, the White Burkett Miller Professor of History at the University of Virginia and former dean of its graduate school. A care...