The US has announced a “further drawdown” of its embassy staff in the South Sudanese capital Juba after more than two weeks of fighting there.
The state department said that, from Saturday, it would no longer provide consular services to US citizens there.
And it urged US citizens to leave on evacuation flights planned for Friday.
Rebels led by the former deputy president have been fighting government forces since last month. At least 1,000 people have died.
About 180,000 people have been forced from their homes.