U.S. ambassador to the United Nations, Nikki Haley, said on Wednesday that Syria's President Bashar al-Assad is a "big hindrance in trying to move forward" to find an end to the country's six-year conflict.

"I'm not going to go back into should Assad be in or out, been there, done that, right, in terms of what the U.S. has done," she told the Council of Foreign Relations. "But I will tell you that he is a big hindrance in trying to move forward, Iran is a big hindrance in trying to move forward."