WASHINGTON - Senator John McCain urged Republican presidential candidate Donald Trump on Monday to apologize to US military families for saying prisoners of war are not heroes in his first direct response to remarks by Trump.Trump drew a barrage of criticism over the weekend after telling a Republican forum he did not think McCain, a Navy fighter pilot imprisoned for more than five years in Hanoi after being shot down, was a hero because he was captured."He's not a war hero," Trump said Saturday at a gathering of religious conservatives in Ames, Iowa. "He was a war hero because he was captured. I like people who weren't captured."In an interview with MSNBC, McCain played down the personal attack and said he did not think Trump owed him an apology, but did owe one to the wider target of his remarks."I think he may owe an apology to the families of those who have sacrificed in conflict and those who have undergone the prison experience in serving our country," McCain said.