If IS takes the pain to fund and coordinate something like this, it is surely because they want to obtain something.  If the attack would not change status quo in any way, there would be no reason to invest time and resources in carrying it out.<p>According to those Western scholars who study IS ideology, it is clear that they adhere to an apocalyptic interpretation of islam where they envisage some kind of final battle against &quot;the armies of Rome&quot;.<p>Whether the attack was intended to serve a strategic or ideologic purpose, or just to make a point, it is clear that the last thing they want is for it to change nothing.<p>So, in a purely rational world, the best reaction would be to change nothing.  Not scale up military presence in Syria, certainly not scale it down, not change any policy, keep on carrying out business as usual, and on the emotional level, mourn, but not fear.  Of course, we do not live in a purely rational world, so whether this route is even possible to follow, I don&#x27;t know.  But I really believe that if we were able to react (or rather non-react) in this way, it would be the very least the attackers wanted.  It would reduce their &quot;heroic deed&quot; to just the meaningless slaugher that it was.<p>As a semi-analogy: After the right-wing extremist Anders Breivik killed some eighty people at a youth camp a few years ago, the Norwegian government more or less handled him as a regular criminal (albeit a high-profile one).  Now he spends his day alone in a prison cell, occasionally whining in the media about not having the latest X-Box or something similar, pretty much revealing to everyone with a working brain what a small character he truly is.  If he had been executed (not possible in Norway, I know....) he could surely have ended up being seen as a martyr by some.