Four US soldiers and their Iraqi interpreter have been killed by a roadside bomb in eastern Baghdad, the US military has said.
The US has launched big operations in several areas of Iraq
The soldiers were on a patrol as part of operations to disrupt the flow of insurgents and weapons into Baghdad.
Nearly 30,000 extra US troops have been sent to Iraq in recent months in an effort to improve security.
US commanders say casualties are mounting as more soldiers patrol outside their heavily-defended bases.
The US military said the four soldiers were killed on Wednesday.
In addition to operations in and around Baghdad, large contingents of US and Iraqi soldiers are heavily engaged trying to drive insurgents from Baquba, in Diyala province, and from the Euphrates valley in Anbar province.
Wednesday's deaths bring the US military toll to 47 this month. The previous three months were the bloodiest for American forces since they led the invasion of Iraq in 2003.