Western leaders continue to discuss possible military action in Syria after a chemical attack killed dozens of people in the formerly rebel-held town of Douma last week.
US President Donald Trump has ordered dozens of air strikes on the Syrian military air base in response to the recent chemical attack in Idlib province.
The Syrian government has agreed to a ceasefire deal with rebel groups across the country, Russian President Vladimir Putin has announced.
The Syrian government has suspended the evacuation of civilians and fighters from opposition-held eastern Aleppo, blaming the rebels for breaking the ceasefire.
An operation to evacuate civilians and rebel fighters from besieged east Aleppo is under way.