Conducting an "extensive background check" for any and all refugees entering this country is more difficult than you'd think.
As someone who was born in the U.S., grew up in a military family, joined the United States Air Force and then gained and maintained a security clearance for more than 30 years, let me explain:
My initial investigation took between six months and a year to complete. I had to submit a 19-page history of my life, including all addresses lived; inclusive dates; names of siblings, their Social Security numbers and birth dates; parents' names, their Social Security numbers and birth dates; and grandparents' names and birth dates. After that, you have to include a list of schools, teachers, friends, jobs, supervisors and three close friends who would vouch for your character before the process began. Then, government investigators selectively traveled to hometowns to interview neighbors, teachers and friends to make a determination if you were trustworthy. Because of my clearance level, I re-accomplished and updated this process every five years. The follow-up investigations even required six months or more to complete.
So I must ask these questions: Where does an investigator start? How do you corroborate and verify times, dates, friends and relatives in war-torn Syria?
If that process takes up to a year for a U.S. citizen, how do you accomplish the same level of rigor in 18 months for a complete unknown from Syria?