The policy of the US should be to recognize Kurdistan as a seperate and soverign country. This goof up by the Brits and the French at the end of WWI must and should be correct now, and without any bloodshed.
Tukey will certainly be upset as will Iran. A look at the map of Pre WWI Kurdistan explains why!. The Shiite in the south would have their own soverign country and the Sunni in the Middle, not a good palce for these guys to be.
The Turks need to understand and work with the Kurds for a peaceful solution to their problem. Iran, will have to learn to accept a peace solution. The Kurds would be a great and reliable ally in the region along with the Shiite in the south. This has been proposed by many knowledgeable people in foreign relations, just do it.
Give the Sunni area to the Kurds and the rest to the shiites.
The Kurds would handle the sunni in short order.