A statement from the U.S. command said the Marine who died Wednesday was assigned to the 1st Marine Expeditionary Force (search). He was mortally wounded earlier in the day in Anbar province, which includes Fallujah.
The statement gave no further details, citing security.
The latest deaths underscore the continued tensions in the region west of the capital despite last month's agreement to end the U.S. Marine siege of Fallujah and hand over security responsibility to an Iraq unit made up of Saddam Hussein's former soldiers.
As of Wednesday, more than 770 U.S. service members have died since the beginning of military operations in Iraq last year, according to the Department of Defense. Of those, more than 560 died as a result of hostile action.