It seems like terrorist activities tend to backfire. I was thinking the same thing with the Boston pressure cooker bombing. There's an event like that, and it ends up uniting people more. 9/11, same thing. Would the point be to break up ties between people? They'd be better off seeding some kind of unreset among the people.
And then for France, they've got French people going against Muslims there now (at least it's not just the US for that type of stuff), and the French stepped up to be the first to defend in Syria or whatever that was.