US Central Command confirmed that two US soldiers were killed in Baghdad and Fallujah, about 60km west of the capital, on Wednesday in separate strikes.
Another two occupation soldiers were killed in Ba'aquba, about 60km north of the capital, when an explosive device detonated near their vehicle, reported our correspondent.
Earlier, wire agencies reported an Iraqi civilian had also been killed in the attack.
An explosive device was also lobbed at a US convoy in the town of Ramadi, about 100km west of Baghdad, before RPGs hit the jeeps, killing and injuring an unknown number of soldiers, eyewitnesses told our correspondent.
Occupation forces immediately cordoned off the area before searching homes for the assailants.
In the town of Habbaniya, some 75km west of Baghdad, three explosive devices also detonated on the main highway as a US convoy drove by, injuring a number of occupation soldiers and damaging three vehicles.
US headquarters in Samarra came under attack for the second time in as many days late on Tuesday, reported our correspondent.
In signs that occupation forces have yet to thwart lawlessness in Baghdad, at least four Iraqis, including two policemen, were killed in an exchange of fire in the Ali Baba and the 40 Thieves Square in the heart of the capital.
Looters were trying to break-in to a money exchange office when the policemen saw them, reported our correspondent.
Two bystanders were also injured.