Five United States soldiers have been killed in Iraq, in a rocket attack on their base on the outskirts of Baghdad.
The U.S. military in Iraq gave few details, saying only that a base in eastern Baghdad came under fire on Monday.
The BBC reports it's the highest single-incident casualty toll for the Americans in more than two years.
Earlier, at least 21 people were killed in twin bomb attacks in the northern city of Tikrit, one of which targetted a mosque.
A large number of the 45,000 US troops in Iraq are due to leave in the summer.
However, during a visit in April, US Defence Secretary Robert Gates said that that troops could, if required by Iraq, stay beyond the withdrawal date of the year end.