Years of dealing with terrorists
To come back to Greg's post, there is no doubt France has had years (if not decades) of experience dealing with Islamic terrorists from north Africa (like from Algeria). The European intelligence was instrumental in the arrest of members of the Al Qaeda network, soon after 9/11. Just this past week, 5 were arrested in Strasbourg. Also, here's France's position on the matter.
I've read this original report based on french intelligence and knowing how serious they are about the matter, have no reason to dispute it.
Raoul