White House said it was “horrified” by reports that rebels in S. Sudan slaughtered hundreds.
171 members of Congress said that the delays had caused distress for children awaiting to be permitted to leave the Congo.
Obama said the genocide was "neither an accident nor unavoidable."
Obama made the announcement at his first White House meeting with Tunisia's prime minister.
CV-22 Ospreys, refueling aircraft and support personnel will join troops already in Uganda.
“We need to be engaged," House Foreign Affairs Committee Chairman Ed Royce (R-Calif.) said. "Where the United States has left a void for economic investment in Africa, China has stepped in."
The actor and director was promoting his Eastern Congo Initiative.
The director will testify before the Senate Foreign Relations panel about the Congo crisis.
Spokesman Jay Carney called the legislation "abhorrent."
Former President Bill Clinton will address the annual African investment conference put together by Sen. Chris Coons (D-Del.).