On CNN's "Fareed Zakaria GPS," Belfer Center Director Ash Carter said although Russian support has bolstered President Assad, Syria's civil war cannot end while he is in power.

Former U.S. Defense Secretary Ash Carter discusses U.S.-China relations, North Korea, the U.S. military, and education. He speaks with Bloomberg's Francine Lacqua and Tom Keene on "Bloomberg Surveillance" at the World Economic Forum's annual meeting in Davos, Switzerland.