Detractors of refugee resettlement, however, point to Tamerlan and Dzhokhar Tsarnaev -- the Boston Bombers -- as evidence to the contrary. The pair of brothers who bombed the Boston Marathon in 2013 were not, however, refugees. They were, on the contrary, children of an asylee, according to the State Department, and the distinction is crucial.



Asylees and refugees share one thing in common: a fear of persecution in the their country of origin. But they differ in important ways. Most importantly, an asylee is self-selected--he arrives in the country from which he's seeking status and applies for asylum. Under international law, people with a well-founded fear of persecution cannot be returned to their country of origin.



By contrast, refugees undergo a much different process. First, they must receive designation as a refugee by U.N. officials, most often in refugee camps. The United States selects only the most vulnerable cases for resettlement, such as those with almost no hope of ever returning to their home country or those who have been tortured.



This selection process and the subsequent vetting undertaken to verify the applicant's biography takes a long time -- up to 3 years -- and is normally exhaustingly thorough. Refugee officers at the Department of Homeland Security travel throughout the region in order to verify claims of persecution and facts about the victims' biography.



If the person claims to have been in a certain place at a certain time, DHS checks. If they claim their house was bombed, DHS confirms that bombs were dropped there (it often uses satellite and drone surveillance for this). The Paris bomber with his fake Syrian passport would have had a very hard time navigating that process.

They were the children of an asylee.