A US soldier killed when his vehicle was struck by a roadside bomb was the 400th US serviceman to die in Iraq since hostilities started on March 20, the military said.
Two other soldiers were wounded when the device exploded next to a two-vehicle patrol, a spokesman said.
The British military has reported 52 deaths so far in Iraq and 16 Italians have died, along with one soldier each from Denmark, Spain, Ukraine and Poland.
