FILE PHOTO - A general view shows damaged buildings at al-Kalasa district of Aleppo, Syria in Aleppo, Syria, February 2, 2017. Picture taken February 2, 2017. REUTERS/Omar Sanadiki Acquire Licensing Rights BEIRUT (Reuters) - The Syrian army and its allies made a sudden advance on Saturday and Sunday into areas held by Islamic State in northwest Syria, a war monitor said, as the jihadist group retr