The CIA has been increasingly active in northern Iraq, making deals with the two main warlords, and many of their subordinates, to get Kurds involved in any invasion of Iraq. The main problem in northern Iraq is not getting Kurds to fight, but to prevent them from trying to take control of oil fields in northern Iraq (just south of the area currently controlled by Kurds.) Apparently negotiations with Turkey, to allow US invasion troops (most likely air mobile troops) to operate from Turkish bases, includes guarantees that the Kurds will not be allowed to set up an independent government. A lot of Kurds in northern Iraq could get behind independence, the Turks have said they would invade themselves if something like that happened. There is already a brigade of Turkish troops in northern Iraq. They just sit there, making the point that a lot more could come in.