Without coming right out and saying so, the government has decided to take back the cities and towns where the anti government forces (Sunni Arabs from the Saddam government, Sunni and Shia Islamic conservatives who want a religious government) have chased out or terrorized the local police and government officials. The American troops have been made available to assist in this operation. In the last year, U.S. forces have learned how to quickly and efficiently deal with the anti-government gunmen. It's dangerous work, and the gangs are not stupid. But the hostile Iraqis are still fighting at a considerable disadvantage. American troops kill the Iraqis quickly, but have to proceed slowly to avoid hurting civilians (who get hit anyway, but in small numbers). The gunmen take advantage of this as much as possible, trying to stay close to women and children whenever possible. The Americans have also learned to play the morale angle. Many of the Iraqi gunmen are out there for the money, or because "it seemed like a good idea at the time." Kill enough of their buddies, especially in a short period of time, and most of them will give up, get rid of their weapons, and go home.
Fallujah is getting "prepped" with a week's worth of smart bombs. Samarra was entered in a rapid attack that basically intimidated the local gunmen, who promptly disappeared. The local government and police were reestablished, and American troops put on call to come back when the Samarra gangs try to regain control in the next few weeks. This is the key factor, getting the gunmen to get involved in that actual battle to decide who is in charge. Without that fight, the gunmen will wait until the Americans depart, then start terrorizing and sniping at the cops and bureaucrats. U.S. forces believe they have methods that overcome these terror tactics, and those methods will be put to the test over the next three months.
The gangs in Tal Afar, a city of some 200,000 people on the Syrian border, did not run away. So the fighting has been going on for a week. Over a hundred of the gunmen have died so far and many others are fleeing the area or giving up the gangster lifestyle. This town has become a major crossing point for men and guns coming from Syria, and the battle there has interrupted that flow. If the government presence remains in Tal Afar, resistance will grow weaker in other parts of Iraq, and the anti-government forces will shift to another crossing point.