Counterterrorism data is clear: Most of the terrorists on American soil do not come from the ranks of refugees but are individuals who are born here and who become vulnerable to recruitment because of mental illness, social marginalization, issues of discrimination and other factors that have nothing to do with admitting refugees into our country.

Meanwhile, the vast majority of war-torn Syrian refugees are fleeing terrorist groups. But they are at risk. Experience from many conflict zones teaches us that the longer these refugees are left to languish in despair in camps the more prone they become to radicalization. Just as gangs attract youth in inner cities, terrorists are adroit at exploiting the most vulnerable who might turn to them for security, justice and even hope. Young men, in particular, gravitate to perceived models of strength and protection. In my book “Talking to Terrorists,” I wrote about a young Chechen in a refugee camp in the Russian Republic of Ingushetia, who explained that his father had been crippled by the conflicts and the youth wanted to join the “Islamic brothers” (meaning Chechen terrorist groups) because they, unlike his father, “were real men.”

There are cases where resettled refugees have become terrorists, but the examples are very rare, and the radicalization most often happened after they entered the United States. Since 2007, a small number of Somali refugees in Minnesota joined the Shabab in response to events happening in Somalia, which played into their own traumatic memories and failure to integrate well here. It bears noting that those who became terrorists left the United States to fight for Somalia rather than attacking the country that gave them refuge.

No doubt the Boston Marathon bomber Tamerlan Tsarnaev comes to mind as a counterexample. His parents came to the United States, where they sought asylum, while Tamerlan, at the age of 16, was left behind for almost two years, waiting to join his family. He was not an extremist when he entered our country. He was radicalized primarily through Internet seduction, well after he arrived. And his first impulse, just like that of the Somalis, was to join the fighters overseas.