It is customary to write incredulously about Assad that “he kills his own people,” meaning Syrians. That is surprising to westerners, but to someone familiar with the Middle East it is expected. Why, because they are not “his people,” they are Sunnis, while Assad is an Alawite. The Alawite are an ethnic-religious minority (about 12%) in Syria, who are considered heretics by the mainstream Sunni Muslims, who constitute the majority of Syrians. The Alawites are considered akin to the Shia as far as the Sunni are concerned. Their center is the north-west of Syria around Latakia. In the Middle East adherence to clan and tribe takes precedence over national affiliation.
When Syria was founded the Sunni were of course in control and the Alawites were excluded from most roles, except the armed forces. Big mistake, they grew powerful within the Army and then the Head of the Air Force Gen. Hafez Assad staged a coup and took over from the Sunni. From outside it may have seemed like the take-over by a progressive Ba’ath Party which was both secular and nationalist, but from within it was seen to be the take-over of Syria by the Alawites. Since then they have fought the Sunni at every turn to retain their dictatorial control. In a Muslim Brotherhood uprising in 1982, Hafez Assad bombarded the town of Hama and killed ca. 30,000 Syrians. No matter, they were Sunnis. The Alawites know that if the Sunni ever take over power from them there will be a blood-bath and it will be Alawite blood that flows. So in order to prevent that they are prepared to kill “their own people,” all Syrians who are Sunnis, even with chemical weapons, and this includes both IS and the democratic opposition. As far as the Alawites are concerned they are all “terrorists.”
This phenomenon exists throughout the Middle East. The nation states that exist are really the invention of the western powers, Britain and France, after WWI. Iraq should really be three states, Shia, in the south, Sunni in the center and west and Kurdish in the north. Likewise Syria is a quilt of Alawite, Sunni, Kurd and other minorities. Maybe the whole Middle East would be better served by redefining states according to their ethnic/religious make-up than pretending that such states as Syria and Iraq can actually cohere and become similar to the western tradition. After all most European States are based on linguistic/ethnic tribes, such as Germany, Hungary, Czechs, etc. It took one hundred years for the Balkans and Russia to rearrange themselves into a patchwork of ethnic states. The evolution of the Middle East is still very much in flux.