If you look, the strategic thrust here is to put more combat troops in trouble spots and try to rein in the Shia militias, who we have not really fought against. This would most likely bring a couple million more trigger-fingers (or IED detonators) to bear on our supply lines, prompting some additional reaction in defense.

Since the whole deployment is hopelessly vulnerable from the supply-chain standpoint (no number of HUMVEE escorts will make it secure), the likely response will be large and blunt, designed to deter rather than actually prevent, increasing guerrilla attacks; likely much in the style of Israel vs Palestine.

Once we start blowing up populated apartment blocks with A-C130-fired howitzer shells to wipe out suspected safehouses, it's all downhill from there.