The United States says it has safely evacuated its citizens from South Sudan's rebel-held town of Bor, as fighting between rebels and pro-government forces continues.
State Department officials say U.S. citizens and others from its "partner nations" were flown from Bor to the capital, Juba, on U.N. and U.S. civilian helicopters early Sunday. A day earlier, the U.S. military said four U.S. service personnel were injured after unidentified gunmen shot at U.S. aircraft attempting a similar operation.
On Sunday, President Barack Obama told Congress he "may take further action" to protect Americans in South Sudan.
Mr. Obama is on vacation in Hawaii, but he said in a letter to congressional leaders that about 46 U.S. troops were deployed Saturday to help with the evacuation. That is in addition to 45 troops deployed to reinforce the U.S. Embassy in Juba.
South Sudan's government says rebels overran the town of Bor in Jonglei state - the scene of some of the worst of the recent fighting.
Clashes began last week in Juba after President Salva Kiir, a member of the Dinka ethnic group, accused former vice president Riek Machar, a Nuer, of attempting a coup. The government says more than 500 people have been killed, and the unrest has forced tens of thousands of people to flee their homes.
Meanwhile, a South Sudan military spokesman says the government has lost control of Bentiu, the capital of oil-rich Unity State. However Juba officials say the rebels are not in control of any oil fields in the state, and that the fields are still operating.
The U.N. Mission in South Sudan said Sunday that all non-critical staff in Juba are being evacuated to Uganda as a precautionary measure.
United Nations Secretary-General Ban Ki-moon called on South Sudan leaders Sunday to find a "political means" to address the conflict. He said the continued violence poses a "dangerous threat" to the future of the young country.
About 35,000 civilians are believed to have fled to U.N. compounds since the unrest began.
South Sudan is the world's newest country, gaining independence from Sudan in 2011.