Here's an article that provides a little more context than the OP:
Much attention has been focused on the security vetting refugees must go through before they come to the United States, particularly after it was revealed that one of the terrorists in the Paris attacks entered Europe through a refugee processing center.
Several federal agencies, including the State Department, the Department of Homeland Security, the Defense Department, the National Counterterrorism Center and the Federal Bureau of Investigation, are involved in the process, which Deputy State Department Spokesman Mark Toner recently called, "the most stringent security process for anyone entering the United States."
READ: Donald Trump: Syrian refugees a 'Trojan horse'
These agencies use biographical and biometric information about applicants to conduct a background check and make sure applicants really are who they say they are.
The applicant is interviewed by a DHS officer with training in this screening process as well as specialized training for Syrian and Iraqi refugee cases.
And refugees from Syria actually go through another layer of screening, called the Syria Enhanced Review process.
"With the Syrian program, we've benefited from our years of experience in vetting Iraqi refugee applicants," a senior administration official recently told reporters. "And so the partnerships we have today and the security checks we have today really are more robust because of the experience that we've had since the beginning of large-scale Iraqi processing in 2007."
Another senior administration official noted that the refugee screening process is constantly refined.
What are the challenges associated with vetting these refugees?
Given the abysmal security situation in Syria and the fact that the United States does not maintain a permanent diplomatic presence in the country, it's sometimes difficult for U.S. authorities to gather the information they need to thoroughly vet a Syrian applicant.
FBI Director James Comey hit on the issue at a congressional hearing last month, when he told lawmakers, "If someone has never made a ripple in the pond in Syria in a way that would get their identity or their interest reflected in our database, we can query our database until the cows come home, but there will be nothing show up because we have no record of them."
This particularly comes into play when trying to evaluate an applicant's criminal history.
"In terms of criminal history, we do the best we can with the resources that we have," one senior administration official said.
Another official emphasized that the vetting process is a holistic one, and they try to take a broader view of an applicant with the available information they're about to aggregate and verify.
http://www.cnn.com/2015/11/16/politics/syrian-refugees-u-s-applicants-explainer/
