Four US soldiers have been killed in Iraq in a series of incidents since Thursday night, the US military says.
US soldiers continue to come under attack
On Friday, a roadside bomb killed one soldier near the town of Balad north of Baghdad. Another died trying to defuse a bomb outside the town of Baqouba.
The US military had earlier said a third soldier had been killed, but officials later said the report had been wrong.
Two soldiers were killed late on Thursday in a mortar attack.
Four soldiers were also injured in the attack, which happened at a military base in Baqouba.
The losses make that 24-hour period the most costly in terms of US lives this month, says the BBC's Chris Hogg in Baghdad.
Over that period, Baghdad alone saw 26 attacks against various targets - whereas on average US forces come under attack about 17 times a day throughout Iraq.
Rockets, mortars and rocket- propelled grenades were fired at targets including the coalition's headquarters, foreign embassies, government buildings and a hotel.
A US military spokesman said five people suspected of carrying out the rocket attacks had been arrested.
He said they were among more than 70 people detained in Baghdad during the latest operations to search for suspected insurgents.
In the northern city of Mosul, unknown gunmen have killed a tribal leader, Sheikh Talal al Khalidi.
The Sunni Muslim leader had been a member of Saddam Hussein's parliament and had joined a new local governing councils set up by the Americans.
American forces have also confiscated two surface-to-air missiles in a search west of Baghdad. Military sources said they were capable of being used against coalition planes.
The US military has continued to bombard locations around Baghdad, in an effort to drive out armed opponents of the American-led occupation.
Meanwhile, an advance contingent of Japanese military personnel has set off on a humanitarian mission to Iraq, paving the way for the future deployment of about 1,000 troops to aid reconstruction efforts.
They are part of a 40-strong advance team who are travelling to Kuwait and Qatar to prepare for the arrival of a larger unit in January.
Most of the Japanese troops will be based in south-eastern Iraq, where they will help restore water services, offer medical aid and rebuild schools.