MG_M, of course it works both ways, particularly when you deal with the moderates but in this situation we're not, we're dealing with extremists who generally are disillusioned individuals being and preyed upon by fundamentalist extremists who want to shape Islam in a way the majority don't.
Europe's porous borders are not going to help us prevent these people seeping back in. I hate to say it but we're going to have to rely on closer intelligence oversight of communications to catch these people and draw together their networks.
The bigger game is that we need play to the 99% of Muslims and get them to purge the extremists - that's the real trick.
The problem then become how do you manage your own right wing nutters such that you can forge a working alliance with other faiths. We need to address that too.