Step1 in defeating them is so easy:
Severely punish everyone buying isis oil.
Assesinate them by cia if req'd.
But somehow, the super power with oil addiction is far too sensitive when it comes to oil interests.
Quit that oil addiction and hit the buyers hard.
Maybe put radioactive tracers in the wells, and close down all refinaries where the trace shows up.
Especially if it is a US owned refinary. Bomb it if you must.