I find it ironic that the majority of Iraqis, especially Iraqi Arabs and nationalists, are determined to keep Iraq united, given that Gertrude Bell, with T.E. Lawrence (of "Arabia"), drew Iraq's borders.
The US occupation has been very different from the British occupation of the 20th century. The US could have split up Iraq, but left it up to the Iraqi people to decide. The British, on the other hand, combined Mosul, Baghdad, and Basra and called it Iraq. The British exploited Iraq's oil resources. The Americans have not. Incidentally, two huge oil contracts (to two European companies) were signed today in Baghdad.