A roadside bomb killed an American soldier in Baghdad Wednesday, according to the US military, making May the deadliest month for the US military since September.
A statement said the soldier died of injuries sustained when the bomb exploded near a patrol in eastern Baghdad.
An Associated Press tally showed that at least 20 American service members died so far this month, compared with 25 in September.
Four US civilians also have been killed in Iraq since Friday.
The spike in deaths came as US forces were facing a June 30 deadline to withdraw from urban areas according to a US-Iraqi security pact.
In all, at least 4,302 members of the US military have died in Iraq since the began in March 2003, according to the AP count.