Refugees and Terror

We've seen anecdotal evidence that the vetting refugees receive doesn't stop them from turning terrorist. We've also seen arguments that we shouldn't expect it to given the paucity of information actually available to vet people coming from failed states, war zones, or enemy states like Iran.

Now we have something like a statistic from James Comey, head of the FBI: refugees make up 15% of their active terrorism cases.

What we don't get from Comey is a sense of whether these refugee terrorists are motivated by, say, attachment to a drug cartel or to, say, some religious doctrine. The United States admitted 85,000 refugees in 2016 alone, meaning that the 300 cases Comey cites would remain a tiny fraction of the refugee population. Even if it were 85,000 total rather than 85,000 annually, that's just 0.0035%; in fact, it would be orders of magnitude lower when you consider the whole population.

Still, refugees as a whole are a tiny fraction of the American population, so it remains surprising to see them so prominently figuring in terrorism cases. Those refugees from 2016 represent 0.00024% of the American population, and treating the population as a whole would only move the decimal at most a few places: we're still going to be talking way less than one full percentage point, not 15 percent.