A U.S. military-led rescue mission on Sinjar Mountain would almost certainly put American troops in harm's way. But Rhodes insisted that their mission would be strictly a humanitarian rescue and would not constitute a return to combat.

"We don't believe that involves U.S. troops re-entering a combat role in Iraq," he said. "It involves frankly a very difficult logistical challenge of moving folks who are in danger on that mountain into a safer position."

Rhodes also suggested the U.S. would undertake a rescue mission with help from allies, including Kurdish forces that are receiving arms from the U.S., and the British.