The Rapid Response Division of the Raqa civil defence excavate the site of a mass grave near the northern Syrian city of Raqa on February 19, 2019. Fadel Senna / AFP
Syrian shepherds herd sheep past a US military convoy near the town of Tal Tamr in the northeastern Syrian Hasakeh province, by the border with Turkey, on April 14. Delil Souleiman / AFP
Smoke rises behind destroyed vehicles and damaged buildings in the village of Baghouz in Syria's eastern Deir Ezzor province near the Iraqi border, a day after ISIS was declared defeated by the US-backed Kurdish-led Syrian Democratic Forces (SDF), March 24, 2019. Giuseppe Cacace/ AFP
Children cross the road as cars drive by in the northern Syrian city of Raqa, the former Syrian capital of ISIS, on May 1, 2019. - The Kurdish-led Syrian Democratic Forces overran Raqa in 2017, after years of what residents described as ISIS's brutal rule, which included public beheading and crucifixions. Delil souleiman / AFP
The Rapid Response Division of the Raqa civil defence excavate the site of a mass grave near the northern Syrian city of Raqa on February 19, 2019. Fadel Senna / AFP
Syrian shepherds herd sheep past a US military convoy near the town of Tal Tamr in the northeastern Syrian Hasakeh province, by the border with Turkey, on April 14. Delil Souleiman / AFP
Smoke rises behind destroyed vehicles and damaged buildings in the village of Baghouz in Syria's eastern Deir Ezzor province near the Iraqi border, a day after ISIS was declared defeated by the US-backed Kurdish-led Syrian Democratic Forces (SDF), March 24, 2019. Giuseppe Cacace/ AFP
Children cross the road as cars drive by in the northern Syrian city of Raqa, the former Syrian capital of ISIS, on May 1, 2019. - The Kurdish-led Syrian Democratic Forces overran Raqa in 2017, after years of what residents described as ISIS's brutal rule, which included public beheading and crucifixions. Delil souleiman / AFP
The Rapid Response Division of the Raqa civil defence excavate the site of a mass grave near the northern Syrian city of Raqa on February 19, 2019. Fadel Senna / AFP