President Trump has said the war against ISIS is over, and all U.S. troops will leave Syria within a month. Nader Hashemi, director of the Center for Middle East Studies and an associate professor of Middle East and Islamic Politics at the University of Denver's Josef Korbel School of International Studies and the co-editor of Sectarianization: Mapping the New Politics of the Middle East (Oxford University Press, 2017), discusses the sudden shift in U.S. policy there and what's happening with the ceasefire in Yemen.