The Turkish-backed military campaign in northern Syria has drawn condemnation from the US, which is supporting some Kurdish forces in the region.
It has long been suspected and now an official investigation reportedly concludes that government troops were behind two toxic gas attacks in Syria.
The Pentagon says US-led coalition aircraft have been scrambled in Syria to protect American special ground forces from attack by government jets.
Striking footage has emerged of children being pulled from the rubble of a building flattened by air strikes in Syria.
There has been heavy fighting in Aleppo as Syrian government forces and rebels battle for control of the city.
Thousands of displaced residents have streamed back into Manbij in northern Syria, now that the last ISIL extremists have fled their former stronghold.
The people of the northern Syrian city of Manbij have been celebrating their liberation from the so-called Islamic State group.
The United Nations says it is talking to Russia about getting a longer halt to hostilities, to help the two million people trapped in the divided Syrian city of Aleppo.
The United Nations is calling for an urgent humanitarian ceasefire to be established in the Syrian city of Aleppo.