This whole thing is a joke! Isis got its start because the Baathists and Sunnis wanted their power back in Iraq. I also believe someone from the states financially supported them to keep the Kurds at bay and go into Syria, keep war going since it's big business. Assad of Syria backs them because they were taking out all the rebel groups poping up to take him out. Russia is supporting Assad and the US doesn't seem to know who to back.
They don't want to support any rebel group not knowing what they'll turn into. Can't or won't support the Kurds beyond small arms so as to not upset the Turks. Iran and several other middle eastern states have gotten involved, it's just a crazy mess and in the end the innocent civilians are the ones getting killed!
This is what happens when you have a regime that invades a country because they want the oil and to stop the leader from selling his oil for another currency, doing all this with out a plan for after the war.