I suspect the nuances of Middle Eastern politics is beyond us all. There are so many vested interests, US, Qatar, Russia, Saudi, Turkey, Iran, Iraq, Israel and so on all have their ideal outcome, support different militias explicitly or covertly, and it by definition if one country gets it's way it will be at the expense of someone else.
Assad is an obnoxious dictator, as was Saddam and Gaddafi, but regime change has not made for a better country for the indigenous population there or the world a safer place.
The foreign policy actions of Bush, Blair, Obama and Cameron have created a power vacuum and the consequent toxic soup within those countries that has allowed ISIS to flourish.
The internet has made the world a flatter, more connected place, so you don't necessarily need training camps in the Middle East to create terrorists and mayhem, just an alienated, disaffected bunch of angry young men (and women) with an internet connection. We learnt that on 7/7.
Excellent post