Four US soldiers have been killed in roadside bombings in Iraq, three in an attack in the north and another in Baghdad, military officials said.
Exact locations were not given as next of kin had not yet been notified.
The attack in the north of Iraq was the deadliest single incident involving the US military in five months.
At the end of June, US-led forces withdrew from Iraqi urban areas, leaving responsibility in the hands of the Iraqi police and army.
About 4,340 US troops have been killed in Iraq since the 2003 US-led invasion.
Earlier in the day, Iraqi police said a roadside bomb in the northern town of Amirli, south of Kirkuk, killed the local police chief and at least four of his colleagues.
There was also a bomb attack targeting a senior Iraqi medical official in eastern Baghdad, which left one minister of health employee dead.
No details are available about the bombing which killed the three soldiers on Tuesday. The fourth soldier was on patrol in southern Baghdad when he was killed, the army said.
On Monday, at least 14 Iraqis died in bomb attacks in cities across the country.
Iraq has seen an increase in violence since the US-led pull-back in July.
Casualty figures are still well below the worst levels of 2006 and 2007, when more than 2,000 Iraqi civilians were being killed every month during the anti-US insurgency and in sectarian strife.