This is something I already knew, and it's why I'm opposed to further intervention – by anyone – in Iraq

Rather than bombs, I would recommend inviting ISIS/ISIL to the bargaining table.
Put on your big girl pants. State your goals publicly. Sign and adhere to the Geneva Convention. Take and hold territory by the standards set by your neighbors and potential allies a generation ago, form a stable, non-tyrranical government in the areas you take, and you can sit at the grownups table be on the path to U.N. Recognition.

The Disintegration of the Iraqi State Has Its Roots in World War I
Created by European powers, the nation of Iraq may be buckling under the pressure of trying to unite three distinct ethnic groups