The Shi'ite militias that resist ISIS, where the Iraqi army is
incompetent to do so, hate Sunnis
and intend
to expel them from any areas they capture from ISIS.
This is likely to force Sunnis to support ISIS even if they detest
ISIS's oppression and cruelty. Unless they have somewhere else to
turn, and at present they don't.
US Republicans want the US
to intervene
against ISIS in Syria.
I don't think the killing of one US journalist, on top of so many
others murdered by ISIS, is particularly important. I don't think
ISIS is close to attacking the US itself. Whether this sort of
intervention is right depends mainly on its effects on the region
itself. I can see the reasons in favor, but I also worry that things
can go wrong in ways we are not likely to anticipate.
US military support for Kurdistan makes sense because Kurdistan is a
nation fighting a conventional war. It has an army that is loyal to
something more than its pay. In addition, Kurdistan is not likely to
fall into brutality comparable to that of ISIS or the Shi'ite
militias.
The use of drones to attack ISIS poses no special ethical issue
because the targets are military units, typically equipped with
unmistakable military vehicles or heavy weapons — not cars,
houses and groups of people standing around, that might well have
civilians in them.
Can/will Kurdistan protect Sunni Arabs that wish to join it? Can it
offer them a way out of support for ISIS?