I think it's worth considering much stricter controls over countries that terrorists largely are coming from. Bans should be out of the question though.
What if they come from here? You know, when I read about all the precautions that have to be taken everywhere, from airports and airlines to art galleries and Christmas markets, I wonder how we as a society would react if instead of coming from one of the big three religions all these attacks were from one small cult. Would we ban the cult entirely?