The two major branches of Islam, Sunni and Shia, are often in conflict. Assad is a Shia, the rebels against him are Sunni. Iran, a Shia state, has forces in Syria supporting Assad. The Jihadist terrorists like Al Queda and ISIL have their own brand of Islam. They attack other Muslims primarily but hate Christians and Jews as well. They are self-regenerating. When Al Queda was crumbling ISIL was formed. Now that ISIL faces attacks in Iraq and Syria another Jihadist faction is forming in Syria.