In the wake of the Paris attacks, many are trying to connect refugees to terrorism. I’ve noted elsewhere that despite millions of refugees having been admitted since the U.S. refugee resettlement program began in its current form in 1980including hundreds of thousands from the Middle Eastnot a single refugee has committed an act of terrorism in the United States.

Detractors of refugee resettlement, however, point to Tamerlan and Dzhokhar Tsarnaevthe Boston Bombersas 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.

For terrorists, the U.S. refugee process is the worst possible avenue in which to travel to the United States. The background checks involved are the most rigorous and the most extensive of those undertaken on foreign nationals coming here. This is likely why every 9/11 hijacker and all other foreign persons who’ve committed acts of terrorism were non-refugees—they were mainly student or tourist visa holders.

Asylum, on the other hand, is much a more attractive route in for a would-be terrorist if they’re already in the desired country. If you want to forestall removal, you can apply for asylum, even knowing you are unlikely to receive it. This is what one Paris attacker did. He applied for asylum and then traveled to France for the attack. He was not a refugee in any sense. Neither the U.N. nor any country in Europe or elsewhere recognized him as a refugee, and it is wrong to claim that he was.

In the United States, we have the luxury of being able to screen Syrians before they arrive. Europe simply cannot. Syrians arrive in boats or by foot in numbers too great for European countries to vet thoroughly. U.S. vetting, by contrast, would likely have immediately flagged the fake Syrian passport long before the would-be terrorist came to the U.S. That’s why events in Paris has no applicability to the U.S. refugee resettlement process. We can vet.  

Moreover, the Tsarnaev brothers were not themselves even applicants for asylum. At less than 10-years-old, they were too young to be vetted, and they received derivative status from their father who had, indeed, come to the U.S. fleeing war-torn Chechnya. It’s a stretch to claim that the system broke down because agents could not foresee that these schoolboys might one day grow up to be killers.

This case does not show that the vetting process for the asylees was broken either. The Tsarnaevs’ father has not engaged in any acts of terrorism and has led a peaceful life in the U.S. 

The millions fleeing ISIS and Bashar al-Assad need the government to get out of the way of their escape. The refugee program allows that escape and does not offer a promising avenue into the United States for would-be terrorists. It would be a tragedy if we were to lose sight of that. 

See my six reasons for accepting refugees here.

This post has been updated slightly.