The moral reasons for a no-fly zone have only grown as the humanitarian crisis has worsened. The geopolitical incentives are stronger than ever. Now the logistical and practical possibilities are emerging.
There will be a no-fly zone, with or without US participation. Turkey wants it, France is chomping at the bit for it, and at the end of the day the rest of the world will realize that there is at least one more domino that needs to fall.