Mr. Trump’s policy director, Stephen Miller, said in an interview with The Wall Street Journal on Monday, “The best way to prevent continued radicalization from developing inside America is to suspend temporarily immigration from regions that have been a major source for terrorists and their supporters coming to the U.S.”…

Counter-terrorism and national-security experts who disagreed with a Muslim ban said a geographic immigration policy still raised concerns, because Mr. Trump so far had not detailed which countries would qualify and how he would measure their records on terrorism. Among the questions: Would it apply to Northern Ireland, which has weathered terror attacks that weren’t carried out by Islamic extremists, and Saudi Arabia, the birthplace of most of the 9/11 hijackers that is also a top American ally?…

Muslim community leaders remain unconvinced that Mr. Trump’s policy is changing.

“I don’t know that he knows himself because it’s a minute-by-minute thing based on who is asking the question,” said Ibrahim Hooper, a spokesman for the Council on American-Islamic Relations.