A man walks amid rubble at a damaged site in the province of Daraa, Syria July 11, 2017. REUTERS/ Alaa al-Faqir

A Free Syrian Army fighter walks out of his position in the town of Dael in Deraa, Syria, July14, 2017. REUTERS/Alaa al-Faqir

Syrian children are seen play amidst the rubble of damaged buildings in Deraa, Syria July 15, 2017. Picture Taken July 15, 2017. REUTERS/Alaa al-Faqir

Fighters from the Free Syrian Army's Al Rahman legion are seen inside an underground tunnel in Ain Tarma, eastern Damascus suburb of Ghouta, Syria July 17, 2017. Picture taken July 17, 2017. REUTERS/Bassam Khabieh

A boy eats a corn as he sits in front of a shop in Ain Tarma, eastern Damascus suburb of Ghouta, Syria July 19, 2017. REUTERS/Bassam Khabieh

Boys play table football in the rebel held besieged Douma neighbourhood of Damascus, Syria July 11, 2017. REUTERS/Bassam Khabieh

A Free Syrian Army fighter sits with his weapon in Deraa, Syria July 13, 2017. REUTERS/Alaa Al-Faqir

People load belongings on a truck amidst the rubble of damaged buildings in Deraa, Syria July 15, 2017. REUTERS/Alaa Al-Faqir

Picture used for illustrative purposes. A man uses his phone as he stands amid rubble of damaged buildings at Bustan al-Qasr neighbourhood in Aleppo, Syria July 16, 2017. Picture taken with a wide-angle lens. REUTERS/Omar Sanadiki

Children hold corncobs at Ain Tarma, eastern Damascus suburb of Ghouta, Syria July 19, 2017. REUTERS/Bassam Khabieh

A boy searches for belongings amid rubble of damaged buildings in Deraa, Syria July 13, 2017. REUTERS/Alaa Al-Faqir

Children play in the rebel held besieged Douma neighbourhood of Damascus, Syria July 11, 2017. REUTERS/Bassam Khabieh

A Free Syrian Army fighter sits in his position in the town of Dael in Deraa, Syria, July 14, 2017. REUTERS/Alaa al-Faqir

A Free Syrian Army fighter stands in his position in the town of Dael in Deraa, Syria, July 14, 2017. REUTERS/Alaa al-Faqir

Damaged buildings are pictured at night in the rebel-held area, in the city of Deraa, Syria July 15, 2017. Picture taken July 15, 2017. Picture taken using long exposure. REUTERS/Alaa Al-Faqir

A woman walks with a child amid rubble at Bustan al-Qasr neighbourhood in Aleppo, Syria July 16, 2017. REUTERS/Omar Sanadiki

A man works on a wheel of a vehicle at Bustan al-Qasr neighbourhood in Aleppo, Syria July 16, 2017. Picture taken with a wide-angle lens. REUTERS/Omar Sanadiki

Children walk past rubble of damaged buildings at Ain Tarma, eastern Damascus suburb of Ghouta, Syria July 19, 2017. REUTERS/Bassam Khabieh

Free Syrian Army fighters pray inside a house in rebel-held Al-Yadudah village, in Deraa Governorate, Syria, July 19, 2017. REUTERS/Alaa Al-Faqir

A Free Syrian Army fighter looks out through a window in rebel-held Al-Yadudah village, in Deraa Governorate, Syria, July 19, 2017. REUTERS/Alaa Al-Faqir

Children play inside a damaged bus in the rebel held besieged Douma neighbourhood of Damascus, Syria July 11, 2017. REUTERS/Bassam Khabieh

A man searches for belongings amid rubble of damaged buildings in Deraa, Syria July 13, 2017. REUTERS/Alaa Al-Faqir

Two men chat as they sit amid the rubble of a damaged site in Deraa, Syria July 15, 2017. REUTERS/Alaa Al-Faqir

Fighters from the Free Syrian Army's Al Rahman legion eat together in Ain Tarma, eastern Damascus suburb of Ghouta, Syria July 17, 2017. Picture taken July 17, 2017. REUTERS/Bassam Khabieh

A man walks while using his phone past damaged buildings in Deraa, Syria July 15, 2017. REUTERS/Alaa Al-Faqir

Men work on resurfacing a street in al-Fardos district in Aleppo, Syria July 13, 2017. REUTERS/Omar Sanadiki

Children are seen near rubble of damaged buildings at Ain Tarma, eastern Damascus suburb of Ghouta, Syria July 17, 2017. Picture taken July 17, 2017. REUTERS/Bassam Khabieh

A woman walks with a child past damaged buildings at Bustan al-Qasr neighbourhood in Aleppo, Syria July 16, 2017. Picture taken with a wide-angle lens. REUTERS/Omar Sanadiki