'They have not been integrated into society'.

Could that be because they don't wish particularly to integrate? In UK they tend to keep themselves to themselves, and many Muslim parents won't allow their teenage children to mix with non-Muslim schoolfellows as friends. Living in the same area in large numbers does isolate them from the other folk in the region, and encourages a ghetto mentality.

It's quite hard to reach out to communities which reject us non-Muslims and one feels they almost despise us and our values (or lack of them!)
In case anyone thinks I'm a rampant UKIP racist, my husband is an African Muslim (now a British citizen) and has found nothing but kindness and many friendships here. But he ardently wants to integrate, and has never held himself apart.
I do agree that the terrorist recruiters will seek out disenchanted young people to become bombers, but I have no idea how this can be addressed.