Other trends are harder to pin down, including the threat an individual may pose to the U.S. The vast majority of U.S.-based sympathizers are connected to the group or exposed to its ideology over social media, and the involvement of most pro-ISIL Americans stops there. The data further show that, among those arrested on ISIL-related charges, only 27 percent planned attacks on U.S. soil. And all appear to have been intercepted by law enforcement before they could do any harm.
About 50 percent of those arrested have made the leap to “actual militancy,” traveling or attempting to travel abroad and fight in places such as Syria and Iraq, the study found. A few may even have “reached midlevel leadership positions within the group." However, the total number of Americans seeking to fight for the group has dropped markedly in recent months — an average of two Americans a month since July, compared to nine a month over the preceding year, according to U.S. officials.
That may or may not be good news. Counterterrorism officials have warned that ISIL may be shifting its strategy, encouraging “lone wolf” supporters in the West to stay at home and strike soft targets. Optimistic officials argue that is a consequence of the group’s slowing territorial gains in its heartland of Syria and Iraq. Nevertheless, fears of Al-Qaeda-style strikes abroad have escalated since ISIL carried out its deadliest-ever wave of attacks outside Syria and Iraq in a span of two weeks last month, striking Paris, Beirut and the Sinai Peninsula.
The GWU report reveals one critical strategy deployed by U.S. law enforcement in cracking down on ISIL recruits: informants. More than half the arrests in the study resulted from an investigation that used either an informant or an undercover law enforcement officer. It’s a tactic the FBI has widely employed in counterterrorism operations since 9/11, “with a remarkable conviction success rate,” according to researchers. It has also “caused friction” with communities that are frequently targeted in such stings, especially among U.S. Muslims.
“These tactics are indeed aggressive and can create a reaction with the Muslim community. That’s undeniable,” Vidino said. But the approach is often called for, he argued, because of “the nature of radicalization in the U.S., with a lot of random recruits across the country that you can’t necessarily link to outside groups.”
The cases reviewed — those arrested by U.S. authorities — represent a small fraction of ISIL supporters, including a total of 250 Americans believed to have traveled or attempted to travel to fight for ISIL. There are at least 900 active investigations into alleged ISIL supporters nationwide, according to law enforcement agencies.
Still, those numbers pale in comparison with the alarming rate of ISIL recruitment in Western European countries, which have seen more than 5,000 of their citizens travel to Syria and Iraq to fight in those wars, usually for ISIL. Experts offer several explanations for the stark discrepancy. Above all, they point to certain pockets of disaffected, poorly integrated Muslim youths in places like Belgium, France and the U.K. that produce a disproportionate number of ISIL fighters.
In the U.S., “you don’t have those hotbeds that you see in Europe — neighborhoods or communities where peer-to-peer recruitment takes place,” said Ali Soufan, the CEO of the Soufan Group, a consultancy based in New York City. With a few exceptions, ISIL “hasn’t been able to find fertile grounds in American Muslim communities,” he said. This is, he explained, partly because U.S. Muslim communities are very diverse ethnically and in terms of religious sect, which inclines them towards integration. They’re also among the wealthiest and most educated Muslim communities in the world, he said.
Nevertheless, the GWU study suggests that ISIL will continue to attract a smattering of followers across the U.S. and that arrests are merely a stopgap measure. Countering ISIL’s messaging online will be essential, though what form that response takes is an open question. GWU researchers recommend incorporating willing American Muslims in counter-messaging, as well as encouraging disillusioned American fighters to return home and share their experiences living in the "caliphate" with would-be recruits.
But as they point out, “Because there is no standard recruit profile, there is also no silver bullet that will blunt [ISIL’s] allure.”