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 wounded Syrian girl looks on at a make shift hospital in the rebel-held area of Douma, east of the capital Damascus, following shelling and air raids by Syrian government forces on August 22, 2015. At least 20 civilians and wounded or trapped 200 in Douma, a monitoring group said, just six days after regime air strikes killed more than 100 people and sparked international condemnation of one of the bloodiest government attacks in Syria's war. (Photo by Abd Doumany/AFP Photo)

A Syrian man carries the body of a girl following a reported airstrike on Kafr Batna, in the rebel-held Eastern Ghouta area, on the outskirts of the capital Damascus, on September 30, 2016. Air raids on several rebel-held towns in the Eastern Ghouta region killed at least 17 people including eight children, the Syrian Observatory for Human Rights monitor said. (Photo by Amer Almohibany/AFP Photo)

North Kenya, Liboi. A young Somali refugee crosses a field filled with marabous storks in July 1992. (Photo by Jean-Claude Coutausse)

A man covered with dust sits on a street following a reported air strike by Syrian government forces in the rebel-held neighbourhood of Sukkari in the northern city of Aleppo on May 30, 2016. (Photo by Baraa Al-Halabi/AFP Photo)

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)

People who fled the violence from Islamic State-controlled northern Syrian town of al-Bab arrive in the rebel-held outskirts of the town, Syria February 3, 2017. (Photo by Khalil Ashawi/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)