Syrian refugees sit behind barbed wire as they wait to cross into Macedonia at the Greek-Macedonian border, near the village of Idomeni, August 21, 2015. (Photo by Yannis Behrakis/Reuters)

Internally displaced Syrian children stand at the entrance of their makeshift shelter that is an underground cave in Om al-Seer, southern Idlib countryside, Syria December 26, 2015. (Photo by Khalil Ashawi/Reuters)

A young Free Syrian Army fighter holds a rifle in Haresta neighbourhood of Damascus January 16, 2013. (Photo by Goran Tomasevic/Reuters)

Syrian refugee boys play with toy guns at Eminonu district in Istanbul, Turkey, 08 January 2019. (Photo by Sedat Suna/EPA/EFE)

Indian artist Sudarsan Pattnaik works on a sand sculpture depicting drowned Syrian boy Aylan Kurdi at Puri beach, some 65 kilometers away from Bhubaneswar, on September 4, 2015. Charities helping refugees saw a surge in donations on September 4 across Europe as people shocked by the heart-rending images of a drowned Syrian boy on a Turkish beach dug deep to help out. The photos of the lifeless body of three-year-old Aylan Kurdi, lying on a beach in Bodrum, Turkey, have triggered a wave of emotion across the continent, despite deep divisions among European governments on how to deal with the crisis. (Photo by Asit Kumar/AFP Photo)

Newly-wed Syrian couple Nada Merhi, 18, and Hassan Youssef, 27, have their wedding pictures taken in front of a heavily damaged building in the war ravaged city of Homs on February 5, 2016. A Syrian photographer thought of using the destruction of Homs to take pictures of newly wed couples to show that life is stronger than death. (Photo by Joseph Eid/AFP Photo)

Syrian government troops patrol the newly captured al- Sakhour neighbourhood in the eastern part of the northern city of Aleppo on December 7, 2016 Rebels in Aleppo called for a five- day truce and the evacuation of civilians Wednesday after losing more than three quarters of their territory including the Old City to a Syrian army offensive. (Photo by George Ourfalian/AFP Photo)

A Syrian boy looks through a gate as others wait to cross into Syria at Oncupinar border crossing in the southeastern city of Kilis, Turkey February 11, 2016.. (Photo by Osman Orsal/Reuters)