It's not clear to me that killing all the people who hold some particular ideology is the same as genocide. Not everyone who supports a violent Caliphate shares the same ethnicity, and not everyone who has a particular ethnicity supports a Caliphate, by way of one example.
Even in ISIS-controlled cities, the majority of the population is not ideologically or dogmatically allied with ISIS, and that's precisely the problem: if you have a town of 400,000, like Raqqa, that is ISIS-controlled, perhaps only a few hundred people in that town are actually affiliated with ISIS in any meaningful way. The rest are people who could not get out fast enough. Control of the town is maintained through whippings, beheadings, crucifixions, and mass executions:
http://www.worldcrunch.com/world-affairs...ories/c1s18693/In conventional warfare, an army opposes an army, each organized and directed by a nation-state. But how do you "wipe out" an insurgency that holds territory not by means of government, but through mass terror and execution? If you bomb Raqqa, what exactly will you accomplish, besides killing civilians who already hate ISIS?
