Sen. John McCain urged Republican presidential candidate Donald Trump on Monday to apologize to U.S. military families for saying prisoners of war are not heroes, in his first direct response to Trump's remarks.

Trump drew a barrage of criticism over the weekend after telling a Republican forum he did not think McCain, a Navy fighter pilot who was held prisoner for more than five years during the Vietnam War, was a hero because he was captured.

McCain played down the personal attack in an interview with MSNBC. He said he didn't think Trump owed him an apology, but did owe one to military families.