It's been one of the U.S.'s biggest goals since the invasion of Iraq: build safeguards that would prevent the country from falling into pieces.
Now, in a few weeks of vicious fighting, those safeguards have reached a breaking point, and the divisions between sects and ethnic groups have hardened in ways that will be hard to reverse. Creating a unifying central government that would divvy up oil revenues, field an army and resolve sectarian differences has suddenly become a much tougher task than many imagined heading into 2006.
The safeguards had been eroding even before the recent wave of violence, but the process became markedly worse beginning with the bombing of a landmark Shiite shrine in Samarra three weeks ago, presumably at the hands of Sunni insurgents. Today, some Shiite and Sunni Arabs are retreating to areas dominated by their own religious sect. The national security forces are increasingly taking on a Shiite tint, infuriating Sunnis and helping to foment their insurgency. In the north, Kurds effectively run their own region and are signing independent oil deals with foreign companies. [Emphasis added.]
Note that these "national security forces" are the same ones Bush keeps insisting are almost ready to restore order in Iraq without 150,000 U.S. troops--and thousands more U.S.-funded contractors--behind them.