You know, considering that there are a lot of people that apply to come here to America, but out of those that apply, only half are accepted. Out of those that are accepted, they are screened as best as they can be, and about another half of those are disqualified as well. The whole process to come here as a refugee takes around 18 to 24 months.
The remaining people? They wait for a place to come here, and when they arrive, they are subject to surveillance for a while.
Out of all the refugees who have come here, ZERO have committed any acts of terrorism.
However........................
If you want to actually do something about terrorists in this country, you should look at how we give visas to people. All the terror attacks in this country that are linked to ISIL are committed by people who (a) are already US born citizens who became radicalized, (b) naturalized US citizens who become radicalized, or (c) people who come here on visas from other countries. Not refugees.
But, saying that the refugees are going to take over the country is a good scare tactic, I see why the GOP is using it so much.