Mr Obama is a personal friend of the new envoy to Sudan
US President Barack Obama has announced that retired Air Force Gen Scott Gration will be his envoy to Sudan.
Gen Gration will lead US efforts to improve the humanitarian situation in the troubled Sudanese region of Darfur.
"Sudan is a priority for this administration," said Mr Obama, in a statement announcing the appointment.
The move follows Sudanese President Omar al-Bashir's decision to expel international aid groups from the Darfur region.
Earlier this month, the International Criminal Court issued a warrant for President Bashir's arrest, accusing him of carrying out war crimes during the Darfur conflict.
Correspondents say the order to expel humanitarian groups was a retaliation for the arrest warrant.
Gen Gration is a close friend of Mr Obama, with many years of experience dealing with Africa, correspondents say.
"[Sudan] cries out for peace and for justice," said Mr Obama in his statement.
"The worsening humanitarian crisis there makes our task all the more urgent."