Email, Marsha Catron, press secretary, U.S. Department of Homeland Security, Dec. 8, 2015

5:41 p.m.

Refugees seeking admission to the United States undergo the most intense security vetting of any traveler seeking admission to our Nation.  They undergo a multi-layered, comprehensive, and robust process involving multiple law enforcement, national security, and intelligence agencies across the government.

Upon the refugee’s arrival to the United States, CBP conducts another security check of the refugee.  If a security-related issue arises even at this late stage of the process, the refugee may be denied admission to the United States.  The process is extraordinarily thorough, and designed to capture late-developing information.

Here’s more info: http://www.uscis.gov/refugeescreening

And a video too:  https://www.whitehouse.gov/blog/2015/11/24/watch-heres-what-refugee-screening-process-looks