Iran still wants their folks to go in and wipe out the opposition. They are clear in their eventual goal to establish a Shii’te dictatorship that is allied with Iran.
They want to win over the Shi’ite population by being their saviors and champions, and shape the future by killing, impoverishing, and ethnically cleansing their likely opponents.
The US s trying to keep Iraq together, so that the groups keep each other in balance - Keep the Kurds in, don’t let Sunnis and Shia massacre each other, etc. Despite the tensions and the agitators, Iraqis still have a strong patriotic sense of themselves as Iraqis - even many Kurds, but desire for independence is most popular among Kurds.
Even if (as seems clear) the Obama administration at the high levels is collaborating with Iran and making secret deals, the bureaucracy of the Defense Department and Department of State continue to work with longstanding policies and relationships in the area, as well as the fundamental opposition of vision and interests (i.e. reality).
Lots of reporting out there, that there will be a deal unveiled with Iran between now and Tuesday, that gives away the store - lifts sanctions, Iran keeps all its nuclear and ICBM gear and facilities, without inspections. The only thing worse would be for the US to start paying for their program and send technical experts to help. So that is no doubt a big factor in what is going on.
The reaction in the region is intense, with war spreading and more countries in the region mobilizing.