I was actually at the rally when he announced this. Trump wants a freeze on immigration from countries that are actively producing a large number of jihadis which, surprise, happens to be predominantly Muslim countries. The premise being, they need more scrutiny and we need time to implement such. Of course I'm sure this whole time he's just been pulling from George W's playbook, acting like an "every guy" who doesn't use big words and wants to appeal to populism.