During last week's Democratic convention, the parents of fallen American soldier Humayun Khan appeared in response to Donald Trump's continuing criticism of Muslim Americans. Much of the audience in the arena and on TV found it moving, but Trump did not. First he tweeted, then repeated his comments about Khan's mother on ABC's This Week program. Trump then acknowledged that Humayun Khan "was a hero," but insisted that his father, Khizr Khan, "viciously attacked" the presidential candidate before millions of people and that the real issue is "Radical Islamic Terror." Glenn Thrush, chief political correspondent for Politico, says the attack has led to more GOP acrimony.