In the first division size operation involving Iraqi forces since 2003, four battalions of Iraqi troops, three battalions of police, backed by two battalions of American troops, swept into western Baghdad (the Abu Ghraib district). The operation is a large scale "cordon and search", capitalizing on newly acquired information about terrorist, criminal and anti-government activities. There are hundreds of people, places and things to look for. By coming in on such a large scale, the enemy has fewer options to get away. 

Such a large force of combat ready Iraqi soldiers and police is the result of two years recruiting and training, and peaceful conditions in most of the country. The only areas where terrorists, or any other anti-government forces, can hide are those containing many Sunni Arabs. That means central Iraq, and especially Baghdad. Eastern Baghdad is largely Shia, but western Baghdad, and thinly populated western Iraq, is Sunni Arab. Last week, American marines chased hundreds of terrorists and gangsters away from hideouts along the Syrian border. Some of them fled to other sanctuaries in western Iraq. Now those hideouts are being surrounded and searched. By hitting the enemy this quickly, and this often, they are more likely to get sloppy, make mistakes, and get caught.