A letter report issued by the Government Accountability Office with an abstract that begins "In 2003, violent conflict in Darfur, Sudan broke out between rebel groups, government troops, and government-supported Arab militias, known as the Janjaweed. The conflict has displaced about 2 million Darfurians and has so affected over 1.9 million others that they require assistance. Since October 2003, the U.S. government has provided humanitarian assistance in Darfur and supported African Union Mission in Sudan's (AMIS) efforts to fulfill a peace support mandate. This report reviews (1) U.S. humanitarian assistance provided to Darfur and the challenges that have been encountered and (2) African Union efforts to fulfill its mandate and challenges that have affected these efforts."