I see it differently. The Sunnis ( including ISIS) are in Syria to overthrow the sovereign and elected government of Bashar Al Assad through terrorism and insurrection. Assad is of the Alawite sect and sympathetic to the Shiites . The Sunnis took over in Aleppo within the sovereign country of Syria . Syria ,under international law, requested assistance from the Russian to push out the Sunni terrorist. That was granted . Now the Sunni bastards are getting slaughtered and have lost Aleppo real bad, The next little party will be a Raqqa , a city known as the Isis HQ in the illegally held sovereign territory of Syria. We can now see President Trump , at the legal request of Assad, committing ground and air power along with the Russian invitees to kill thousands of those gawdless bastards real dead and remove them from Syria 100%! McCain can go to hell.
You accurately provided color commentary as to how they got to where they are. I was simply stated my view of the sentiment in Sunni populated Turkey at the time of the assassination.