US commanders say al-Qaeda has regrouped in northern provinces, including Diyala, after being pushed out of other parts of Iraq.
US commanders also claim that a ceasefire by fighters of the al-Mahdi Army, loyal to Muqtada al-Sadr, a populist Shia figure, is lowering the bloodshed in the country.
Al-Sadr's spokesman said the leader was considering extending the six-month truce after it expires in February.
Al-Sadr, who led uprisings against US troops in 2004 and whose followers were later described by US commanders as their greatest threat, surprised both Iraqis and US forces when he ordered the initial six-month freeze on his group in August.
On Wednesday in Najaf, al-Sadr's spokesman, said: "Yes, there is a chance that the freeze on the Mahdi Army will be extended."
The son of a prominent Shia scholar killed under the government of Saddam Hussein, al-Sadr has wide influence in the Shia south and parts of Baghdad although he does not himself carry religious standing.