Several high-level administration officials have warned in recent months just how challenging [screening Syrian refugees] can be. While they say U.S. security measures are much better than in the past, vetting Syrian refugees poses a quandary: How do you screen people from a war-torn country that has few criminal and terrorist databases to check? …
“I don’t, obviously, put it past the likes of [ISIS] to infiltrate operatives among these refugees, so that’s a huge concern of ours,” Director of National Intelligence James Clapper said at a security industry conference in September …. He added that the government has “a pretty aggressive program” for screening refugees but that he is less confident about European nations.
FBI Director James Comey added in congressional testimony last month that “a number of people who were of serious concern” slipped through the screening of Iraq War refugees, including two arrested on terrorism-related charges. “There’s no doubt that was the product of a less than excellent vetting,” he said.
Although Comey said the process has since “improved dramatically,” Syrian refugees will be even harder to check because, unlike in Iraq, U.S. soldiers have not been on the ground collecting information on the local population. “If we don’t know much about somebody, there won’t be anything in our data,” he said….