I don't think they shelter them, these extremists are born and raised in these countries. Unfortunatly they are exposed to hardcore clerics and fundamentalist Islamic influences. In every country there are people who become disillusioned with the way things are done, they United States has quite a few militia groups and radical groups, Timothy McVeigh, the Oklahoma City bomber was one, in Canada we have had fringe French groups. In the UK and Australia it is Muslim extremists, probably because it is easier for them to get into these countries, for whatever reasons.

Nobody is more extreme in their beliefs than someone who is seperated and living apart from those beliefs.