South Sudan's army has vowed it will take back two state capitals seized by rebelling soldiers.
Army spokesman Philip Aguer told VOA that soldiers backing former vice president Riek Machar control Bor in Jonglei state and Bentiu in oil-rich Unity state, but that the military is "capable of dealing with the rebellion."
"Definitely the army will re-control these areas. It's a matter of days and the army will control Jonglei state and we will work for the reestablishment of the full control of the national army over South Sudan."
He also accused fighters backing Machar of shooting at a U.S. aircraft that was evacuating citizens from Bor on Saturday. The U.S. military did not identify the shooters, but said four of its personnel were injured.
Clashes began eight days ago in the capital, Juba, after President Salva Kiir accused Machar of attempting a coup. Machar has not claimed responsibility for a coup attempt but has called on the army to remove the president from office.
The U.N. humanitarian office says the violence has displaced 62,000 people across five states, and that more than 40,000 have taken refuge on U.N. bases.
U.S. President Barack Obama says 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 Sunday 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.
U.N. 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.
U.N. officials have expressed concern the rift between Mr. Kiir, a member of the Dinka ethnic group, and Machar, an ethnic Nuer, could provoke widespread tribal violence in South Sudan.