What do you want to bet that the French pattern is visible in Britain, which has been (in the Post's words) "a haven for fundamentalists who enjoy traditional British liberties and a generous social welfare system even as they rail against the culture that has given them refuge"?
In fact, there's a good argument that "welfare benefits + ethnic antagonism" is the universal recipe for an underclass with an angry, oppositional culture. The social logic is simple: Ethnic differences make it easy for those outside of, for example, French Arab neighborhoods to discriminate against those inside, and easy for those inside to resent the mainstream culture around them. Meanwhile, relatively generous welfare benefits enable those in the ethnic ghetto to stay there, stay unemployed, and seethe. Without government subsidies, they would have to overcome the prejudice against them and integrate into the mainstream working culture. Work, in this sense, is anti-terrorist medicine. (And if you work all day, there's less time to dream up ways and reasons to kill infidels.)
Appetite-whetting precursor:OpinionJournal.com has posted several items on "terrorist welfare queens" but hasn't made the larger point about entire alienated subcultures being sustained by welfare.
Assigned to: Lawrence Mead, who claimed in his 1992 book, The New Politics of Poverty, that Europe is "about a generation behind the United States" in confronting the social problems created when a discriminated-against group becomes dependent on state aid. Alternatively: Heather Mac Donald, John Podhoretz, John O'Sullivan. … If I knew a neolib who might write this, I'd assign it to them. But I don't. [Bill Clinton?—ed. Not a bad idea! It would make his U.S. welfare reform campaign look globally relevant.]