US Secretary of State Condoleezza Rice said a new security operation in Baghdad appears to be off to "a good start," and she urged Iraq's government to make good use of any lull in sectarian violence.
Rice made her comments on Saturday during an unannounced visit to Iraq.
US military officials say the new US and Iraqi security crackdown in Baghdad has led to a significant reduction in the number and effectiveness of attacks in the capital. Increased security has been in effect for four days.
But in northern Iraq on Saturday, two car bombs killed at least nine people and wounded 60 others in a crowded market in Kirkuk. A suicide bomber caused one of the explosions.
Also on Saturday, the US military said a marine died in combat operations Friday in western al-Anbar province.
The Defense Department announced on Friday that it is sending an army headquarters staff of about one-thousand soldiers to Iraq in March, three months ahead of schedule. That staff will help manage the additional combat troops being sent to Baghdad.