The US airstrikes prompted an emergency meeting by the UN Security Council. Envoys of the US and Russia to the UN have accused each side of failing to abide by the agreement that led to the ceasefire.

"And let me just say for the record that we believe that Russia should in fact be convening an emergency meeting this evening and emergency meeting with the Assad regime which is bombing in defiance of the cessation of hostilities which is continuing its practice of death by a thousand paper cuts in starving Syria's civilians," US ambassador to UN Samantha Power said.

"The way it looks is that the United States really allowed the genie to get out of the bottle having being arming, preparing, training various opposition groups, ignoring the fact that they have been working with al Nusra and other terrorist groups, ignoring the fact that many of those groups which they regarded as moderate opposition were resorting to terrorist tactics and you know, now, they are out there, not about to listen to those in Washington who are trying to reach political agreement," Russia ambassador to UN Vitaly Churkin said.