A rebel fighter carries his weapon as he moves through a hole in a wall in the old city of Aleppo near the frontline against forces loyal to Syria's President Bashar al-Assad December 28, 2014. (Photo by Jalal Al-Mamo/Reuters)

A mosaic artwork, copied from an original painting, is pictured in a workshop in Kafranbel town in the Idlib governorate January 17, 2015. The mosaic workshop with 30 workers, manufactures artistic and revolutionary mosaics in Kafranbel. Each mosaic artwork takes 5 to 10 days to complete. The artists exhibit their artwork in local and international exhibitions, and have a scheduled exhibition this month about the “Syrian Revolution” in Turkey. (Photo by Khalil Ashawi/Reuters)

Internally displaced Syrian children who fled Raqqa city stand near their tent in Ras al-Ain province, Syria January 22, 2017. (Photo by Rodi Said/Reuters)

A Syrian boy receives treatment at a hospital in the regime-held part of Aleppo on October 13, 2016. Syrian state television said four children were killed by rebel rocket fire on a school in a western regime-held neighbourhood. (Photo by George Ourfalian/AFP Photo)

A little girl holding her newborn sister waits for their turn in a queue during a vaccination campaign under the supervision of the Syrian Arab Red Crescent (SARC) humanitarian nonprofit organization, in the besieged Syrian town of Douma, Syria, 23 May 2017. According to a statement from SARC, in the city of Douma some 12,809 children under the age of five were immunized in a vaccination campaign to prevent measles and poliomyelitis. The campaign was the first of its kind with the participation of 100 volunteers. SARC has been delivering vaccines to 17 health centers approved for vaccination campaigns in towns and villages in the Eastern Ghouta area. (Photo by Mohammed Badra/EPA)

Girls sit inside an empty classroom as they pose for a photograph during a celebration marking the end of the school year in the town of Douma, eastern Ghouta in Damascus, Syria May 21, 2016. (Photo by Bassam Khabieh/Reuters)

A man stands near bodies of his young relatives after an airstrike in the rebel held Douma neighbourhood of Damascus, Syria August 22, 2016. (Photo by Bassam Khabieh/Reuters)

Men pull as a boy stands on a soap cutter in a soap factory in Idlib province, Syria January 30, 2016. (Photo by Ammar Abdullah/Reuters)