With the attack on the humanitarian aid convoy, the conflict in Syria reached a new low. The ceasefire so recently agreed between the US and Russia is in danger of total collapse.

The situation in Syria today is on a knife-edge. If the ceasefire is to have any chance at all, there needs to be a complete ban on all military flights over Syria for a limited period – three days at least, though seven would be better.

This would make it possible for the United Nations to resume its humanitarian assistance missions to the people suffering and under siege.

At the same time, it would create scope for precise agreements within the International Syria Support Group on coordinated measures against IS and al-Qaida and for the resumption of negotiations on a transitional government for Syria.