The Center for National Security at Fordham Law has an annual report on cases involving the Islamic State (ISIS) that have appeared in US Federal court.  As of 2016, 101 such cases have been recorded.  That is a small number from which to draw statistical lessons, but it is comprehensive of the cases brought to trial.

Most of these cases — each individual involved is considered a separate “case” by the study — are still pending before the courts.  However, of the 45% of cases that have resulted in conviction, the average sentence is only 9 years.  This is in part because most of the defendants have no criminal history.  The fact that they have no criminal history before attempting to take up arms for the caliphate is a major reason why a free and open society like the United States is so vulnerable to these attackers.

Most of them are also American citizens.  Not all of them are.  12% are refugees, or have overstayed their visa on a visit, or otherwise are without legal residency.  But far and away most of them are American citizens who have no love or loyalty for their own country.  “Despite the fact that nearly 80% of the charged defendants are U.S. citizens,” the report says, “an identification with foreign conflicts rather than with American politics and society is apparent across the sample of indicted individuals.”  In other words, they don’t identify themselves as Americans.  They identify themselves as Muslims, loyal not to the land of the free but to foreign entities that they feel are under attack by America.

There are other strong similarities.  Almost all of them want the caliphate.  90% of them have never been found to be mentally ill.  90% of them do not use drugs.  Most are in their 20s.  They are mostly a young, clear-eyed, clear-headed generation of young Americans who have rejected their nation in favor of Islam.

They are also all over social media.  90% of the cases involve the use of the internet to try to connect with or understand ISIS.  In fully 60% of cases, ISIS was able to establish two-way communication with them.  It looks as though in most of the cases the initiative was on the part of these American Muslims, however.  ISIS is able to recruit them because, for the most part, they went looking to be recruited.

There are also a lot more of them that we have not heard from yet.  “Although there are only 101 publicly known cases,” the report adds, “the Director of the FBI, James Comey, has noted that over 900 investigations are open and that they span all 50 states.”  Adding that to the 101 we have already seen brought to court, and you have a thousand cases of ISIS infiltration or self-radicalization within the United States alone.  Nine in ten of those cases have not yet resulted in attacks.

Nor is the fact that the FBI aware of them a guarantee of safety.  The Orlando attacker was twice investigated by the FBI, and cleared both times.  He went on to murder dozens in the Pulse nightclub.

Finally, these are just the ones we know about.  There is no reason to believe that the FBI has eyes on every potential terrorist.

Until we figure out how to prevent the radicalization of American Muslims, our main line of defense is broken.  We keep talking about background checks for Muslim immigrants, to ensure that they are not themselves radicals.  However, as this study shows, the majority of the threat comes from born Americans.  That is in line with earlier findings, not just from here but from Europe as well, that show that second generation immigrants radicalize at twice the rate of first generation immigrants.

That a first generation of Muslim immigrants is often succeeded by a radical second generation has been documented by Foreign Policy, PBS, and by statisticians in Denmark.  The first generation came to America or to Europe for reasons they felt strongly enough to make the move.  They understood they were electing to move to a society that was less Islamic, and accepted the trade off.  Their children, born in the West, did not experience the realities that made their parents leave the old world.  They reject the laws and customs of their new society as being opposed to their Islamic identity.  The Danish statistics found that second-generation Muslim immigrants are 218% more inclined to crime than their parents’ generation.

That’s a huge problem.  Even if we get the background checks 100% right, the ones we really have to worry about is their unborn children.  Those are the ones who are most likely to grow up to adopt these violent forms of Islam.  Unless we can solve that problem, we are going to remain very vulnerable to terror from within.