Sen. John McCain

"(Syrian President) Bashar Assad and his friends, the Russians, take note of what Americans say," the Arizona Republican told CNN's Alisyn Camerota on "New Day." "I'm sure they took note of what our Secretary of State (Rex Tillerson) said just the other day that the Syrian people would be determining their own future themselves -- one of the more incredible statements I've ever heard."

Speaking at a conference of religious conservatives in Iowa, Trump was pressed on his recent description of the 2008 Republican presidential nominee as "a dummy."

McCain served as a Navy pilot during the Vietnam War. He was captured after his plane was shot down and was held more than five years as a prisoner of war. The moderator, Republican pollster Frank Luntz, described McCain as "a war hero."