I think the whole "closed/secure border" argument is a complete nonsense. The UK is not part of Schengen so we have 'secure' borders apparently, yet we still have thousands of illegal immigrants who have crossed these secure borders! My understanding is the French tightened border control to prevent any accomplices escaping?
Of greater interest is that following the Russian Airliner tragedy, Beirut suicide bombings and now this maybe a consensus could be built to counter the IS threat. Some indiction on social media that the Russians, at G20, will suggest that we could put differences aside and agree a common policy to counter IS. Not sure the West is at the stage of accepting that Assad might have to stay at least short term and certainly can't see NATO boots on the ground yet. I suspect we will remain reactive and keep our fingers crossed!