Trump called for heavy surveillance of Syrians, Muslims and anyone with possible ties to the Islamic State. He urged the audience members to be vigilant and report anything suspicious they see to the police.
"I want surveillance of certain mosques, okay? If that's okay?" Trump said, as thousands of people in the audience cheered. "I want surveillance. And you know what? We've had it before, and we'll have it again."
Earlier in the week, Trump faced criticism for not immediately rejecting the idea of using a religion-based database to track Muslim Americans. He then faced increased criticism for seeming to agree with the idea in an interview in Iowa on Thursday evening with Vaughn Hillyard of NBC News. In that brief interview, Hillyard asked Trump a series of questions about the possibility of a Muslim database, and the candidate seemed to agree, using the words "certainly" and "absolutely."
Trump said Saturday that he thought he was answering questions about building a wall on the Mexican border. He called Hillyard "some little wise guy who looks like he's 12 years old" and said music was loudly playing during the interview, which was conducted as Trump signed autographs following a town hall in Iowa on Thursday afternoon.
"I was referring to the wall," Trump said. But then he added: "The database is okay. A watch list is okay and surveillance is okay ... I want surveillance of these people that are coming in, the Trojan horse. I want to know who the hell they are."
Trump said part of the reason he wants heavy surveillance is that he remembers watching the World Trade Center fall on 9/11 and hearing reports of "thousands of people" cheering the destruction.
Since the terrorist attacks in Paris this month, many Republican candidates have become increasingly skeptical of Muslims and Syrian refugees. Trump has taken some of the most strident positions -- and he says his poll numbers are going up as a result.
"We've gone way up, because people know that I'm going to protect them," Trump said. "I'm going to protect them at the borders. I don't want the people from Syria coming in, because we don't know who they are. We don't know who they are. And I don't want them coming in."