People walk on rubble of damaged buildings in the besieged town of Douma, Eastern Ghouta. Reuters, file
An affected man puts the aerosol mask on his child while his other daughter gives treatment to her other sister after a shelling attack on rebels-held Eastern Ghouta. EPA
A child receiving oxygen through respirators following an alleged poison gas attack in the rebel-held town of Douma on Sunday, April 8, 2018. Syrian Civil Defense White Helmets via AP
Syrian civil defence volunteers, known as the White Helmets, work around destroyed buildings following reported air strikes on the rebel-held town of Douma. AFP, file
A Syrian child who was injured in shelling on the town of Misraba receives treatment at a make-shift hospital in the besieged rebel-held town of Douma. AFP
A Syrian man pushes out of a crowd after Syrian authorities distributed bread, vegetables and pasta to hungry Douma residents. AP
Russia vetoes a UN Security Council resolution that would have set up an investigation into chemical weapons use in Syria on April 10, 2018. AFP
UN vehicles carrying the team of the Organization for the Prohibition of Chemical Weapons (OPCW). AP, File
Labels of the Organisation for the Prohibition of Chemical Weapons (OPCW) are seen inside a damaged house in Douma in Damascus, Syria April 23, 2018. Reuters
The Syrian government unleashed a ferocious assault on the then-rebel stronghold of Eastern Ghouta on February 18, 2018 aiming to crush militant groups on the doorstep of the capital. Civilans were trapped and many died. AFP
What appears to be white phosphorus incendiaries over Douma during regime bombardment of what was one of the few remaining rebel-held pockets in Eastern Ghouta. AFP, file
A Syrian man helps evacuate an injured victim following Syrian government air strikes on the Eastern Ghouta rebel-held enclave of Douma, on the outskirts of the capital Damascus on March 20, 2018. AFP
A woman gestures as she walks on rubble of damaged buildings after an airstrike in the besieged in eastern Ghouta. Reuters
Syrians search for survivors following regime air strikes on the rebel-held besieged town of Douma in the eastern Ghouta region. AFP
Syrian children sit before a mural on a wall bearing the logo of the Syrian Red Crescent in the Syrian town of Douma in the rebel-held enclave of Eastern Ghouta on the eastern outskirts of the capital Damascus on March 13, 2018. AFP
A shepherd leads his flock away from Douma to safer areas in the rebel-held enclave of Eastern Ghouta, on the outskirts of Damascus, on March 7, 2018. AFP
People ride a horse along a damaged street at the city of Douma in Damascus. Reuters
People walk on rubble of damaged buildings in the besieged town of Douma, Eastern Ghouta. Reuters, file
An affected man puts the aerosol mask on his child while his other daughter gives treatment to her other sister after a shelling attack on rebels-held Eastern Ghouta. EPA
A child receiving oxygen through respirators following an alleged poison gas attack in the rebel-held town of Douma on Sunday, April 8, 2018. Syrian Civil Defense White Helmets via AP
Syrian civil defence volunteers, known as the White Helmets, work around destroyed buildings following reported air strikes on the rebel-held town of Douma. AFP, file
A Syrian child who was injured in shelling on the town of Misraba receives treatment at a make-shift hospital in the besieged rebel-held town of Douma. AFP
A Syrian man pushes out of a crowd after Syrian authorities distributed bread, vegetables and pasta to hungry Douma residents. AP
Russia vetoes a UN Security Council resolution that would have set up an investigation into chemical weapons use in Syria on April 10, 2018. AFP
UN vehicles carrying the team of the Organization for the Prohibition of Chemical Weapons (OPCW). AP, File
Labels of the Organisation for the Prohibition of Chemical Weapons (OPCW) are seen inside a damaged house in Douma in Damascus, Syria April 23, 2018. Reuters
The Syrian government unleashed a ferocious assault on the then-rebel stronghold of Eastern Ghouta on February 18, 2018 aiming to crush militant groups on the doorstep of the capital. Civilans were trapped and many died. AFP
What appears to be white phosphorus incendiaries over Douma during regime bombardment of what was one of the few remaining rebel-held pockets in Eastern Ghouta. AFP, file
A Syrian man helps evacuate an injured victim following Syrian government air strikes on the Eastern Ghouta rebel-held enclave of Douma, on the outskirts of the capital Damascus on March 20, 2018. AFP
A woman gestures as she walks on rubble of damaged buildings after an airstrike in the besieged in eastern Ghouta. Reuters
Syrians search for survivors following regime air strikes on the rebel-held besieged town of Douma in the eastern Ghouta region. AFP
Syrian children sit before a mural on a wall bearing the logo of the Syrian Red Crescent in the Syrian town of Douma in the rebel-held enclave of Eastern Ghouta on the eastern outskirts of the capital Damascus on March 13, 2018. AFP
A shepherd leads his flock away from Douma to safer areas in the rebel-held enclave of Eastern Ghouta, on the outskirts of Damascus, on March 7, 2018. AFP
People ride a horse along a damaged street at the city of Douma in Damascus. Reuters
People walk on rubble of damaged buildings in the besieged town of Douma, Eastern Ghouta. Reuters, file