"ISIS has claimed on multiple occasions the intent to infiltrate terrorists into the refugee flow," said Robert Maginnis, a retired Army officer and terrorism analyst. "One can argue that the Tunisian who drove the truck into the Berlin Christmas market was an immigrant tagged as influenced by ISIS. Certainly ISIS will do whatever it can to infiltrate those coming to this country as well. Time will tell whether they are successful, and meanwhile we are vulnerable."
"Prisons are great recruiting grounds for Islamists, especially in Islamic countries," he said. "We found that to be true in Iraq and Afghanistan, where many vulnerable Muslims were manipulated into radicalism while serving time."