Dan Froomkin writes:

National security adviser Stephen J. Hadley writes in a Washington Post op-ed that Bush "concluded that the strategy with the best chance of success must have a plan for securing Baghdad. Without such a plan, the Iraqi government and its security institutions could fracture under the pressure of widespread sectarian violence, ethnic cleansing and mass killings. Chaos would then spread throughout the country -- and throughout the region. The al-Qaeda movement would be strengthened by the flight of Sunnis from Baghdad and an accelerated cycle of sectarian bloodletting. Iran would be emboldened and could be expected to provide more lethal aid for extremist groups. The Kurdish north would be isolated, inviting separation and regional interference. Terrorists could gain pockets of sanctuary throughout Iraq. . . . "

Note to Hadley: That's all happening already.