of run down apartment blocks where most of those living there have roots in Algeria (a former French colony), Morocco (formerly run by France and Spain) and other parts of north Africa. Some of those involved in the Paris attacks were from Molenbeek, a poor suburb of Brussels with a substantial Muslim population which has been described by Belgian officials as a "breeding ground for jihadists." And there are other cities and towns in France and elsewhere in Europe with large second and third generation immigrant communities concentrated together in poorer areas.

This is a big challenge. Integration in France and elsewhere has been poor even after one or two generations, and there are unemployed, disaffected young men and women from immigrant families who feel excluded and have littleloyalty to the country they were born in.

Instead there is deep resentment. The alienation and boredom they feel makes them easy fodder for radicalization. The Paris attackers are examples of this.

Instead of being devout Muslims committed to fighting against the so-called wicked west, they were losers who dabbled in drugs, alcohol and sex, living on welfare and spending much of their time playing video games and drifting around. Joining up to fight on the fringes of Isis may have given them a new sense of self-worth, purpose, even excitement, they had never felt before. That was probably just as important a factor for the Paris group as any understanding they had of the overall aims of ISIS and its desired caliphate.

Of course the majority of immigrants do integrate