Syrians leave a rebel-held area of Aleppo towards the government-held side on December 13, 2016 during an operation by Syrian government forces to retake the embattled city. UN chief Ban Ki-moon expressed alarm over reports of atrocities against civilians Monday, as the battle for Aleppo entered its final phase with Syrian government forces on the verge of retaking rebel-held areas of the city. / AFP PHOTO / KARAM AL-MASRI