U.S.-led international coalition killed six Islamic State (IS) militias in Syria's Raqqa province, Syrian Observatory for Human Rights (SOHR) reported Tuesday. The observatory said that the coalition carried out several airstrikes targeting IS strongholds in Raqqa, killing six militants and destroying a number of its equipment. Meanwhile, Syrian news agency (SANA) had reported earlier Tuesday the death of 140 IS militants in a Syrian forces raids on Taba'a airport in Raqqa. Raqqa is one of the largest Syrian cities, and considered IS capital in Syria.