Military personnel are being called to help protect the US Embassy in Baghdad after a US soldier was killed in an ambush.
US Secretary of Defense Chuck Hagel is scheduled to visit the city on Thursday.
The attack happened during a visit by the US ambassador to Iraq, Gen John Campbell.
The US military is being called in to help, with US Special Operations forces expected to take part.
The Iraqi military has said it has launched a criminal investigation into the incident.
More to follow.