With the opposition of Turkey, a NATO member, we can't establish a Kurdish state, which would by definition appropriate part of Turkey itself.
Which is why the Turks, our Allies, are content to allow ISIS, their fellow Sunnis, to slaughter as many Kurds as ISIS can. It will be a genocide, but the Turks are no strangers to genocide, having perpetrated one against the Armenians in 1915, although we are forbidden to mention it.
These are real and horrific genocides, as opposed to the disgusting and contemptible and false accusations of genocide tossed about recently.
At any rate, ISIS will soon have a broad swath of the Middle East ethnically cleansed of Yazidis, Kurds, Chaldean Catholics, Syrian Orthodox, Shiite Muslims, Jews (of course!), and anyone else they don't like.
And the world will have done next to nothing to stop it.