A car bomb has exploded next to a US army patrol in the northern Iraqi city of Mosul, killing one soldier and wounding three on Thursday.
In a second attack on Thursday, a soldier was shot dead in an exchange of fire.
The death brought the number of US troops killed in action to 1116 since the US-led invasion of Iraq in March 2003.
US troops have been battling to keep order in Mosul, where battles broke out in November with resistance fighters when almost the entire police force in Iraq's third-largest city deserted.
The 8000-strong US force in Mosul has said it is steadily returning stability to the city.
On Thursday, a resident tipped off US troops to the presence of six roadside bombs and the devices were defused, the military said.