The US military said a Fourth Infantry Division soldier was killed and two others wounded on Tuesday evening when their convoy was hit by an improvised explosive device (IED) in Al-Taji, north of Baghdad.
Another US soldier was killed and a second wounded early on Wednesday when their four-vehicle convoy hit a roadside IED, also north of Baghdad.
Aljazeera's Baghdad correspondent reported that four US soldiers were killed after their vehicle fell into the Al-Sinaeya river in Baghdad.
Eyewitnesses told him that the incident happened late on Tuesday evening.
They said a US helicopter picked up the vehicle from the river shortly after the incident and took the bodies away.
At the moment, it is not clear whether the soldiers were killed in a resistance attack or in an accident.
At least 122 American soldiers have now been killed in Iraq since the White House declared major combat operations in Iraq over on May 1.
Meanwhile, an Iraqi boy was killed and at least four people were wounded on Wednesday in the first clash between US forces and Shia Muslims in Baghdad since Saddam Hussein was toppled in April.