[gravitypunch]

...fragmentation? The U.S. invasion and the Bush administration's initial occupation policies decisively smashed Iraq's fragile "national" sense of self. Since then, the Bush administration, a motor for chaos and fragmentation, has destroyed the national (if dictatorial) government, allowed the capital and much of the country (as well as its true patrimony of ancient historical objects and sites) to be looted, disbanded the Iraqi military, and deconstructed the national economy.
Ever since, whatever the administration rhetoric, the U.S. has only presided over the further fragmentation of the country. Its military, in fact, employs a specific policy of urban fragmentation in which it regularly builds enormous concrete walls around neighborhoods, supposedly for "security" and "reconstruction," that actually cut them off from their social and economic surroundings. And, of course, Iraq has in these years been fragmented in other staggering ways with an estimated four-plus million Iraqis driven into exile abroad or turned into internal refugees.

According to Pepe Escobar of the Asia Times, there are now at least 28 different militias in the country.
The longer the U.S. remains even somewhat in control, the greater the possibility of further fragmentation. Initially, the fragmentation was sectarian -- into Kurdish, Sunni, and Shia regions, but each of those regions has its own potentially hostile parts and so its points of future conflict and further fragmentation. If the U.S. military spent the early years of its occupation fighting a Sunni resistance in the name of a largely Shia (and Kurdish) government, it is now fighting a Shia militia, while paying and arming former Sunni fighters, relabeled "Sons of Iraq."

Without a real national government, Iraq has descended into a welter of militia-controlled neighborhoods, city states, and provincial or regional semi-governments.
Despite all the talk of American-supported "reconciliation," Juan Cole described the present situation well at his Informed Comment blog: "Maybe the U.S. in Iraq is not the little boy with his finger in the dike. Maybe we are workers with jackhammers instructed to make the hole in the dike much more huge."