NAIROBI, March 9, 2025 (BSS/AFP) - The United States has ordered all non-emergency staff in South Sudan to leave, the State Department said Sunday, as rising tensions provoke international concern.

A fragile power-sharing agreement between President Salva Kiir and First Vice President Riek Machar has been threatened by recent clashes between their allied forces in the northeastern Upper Nile State.

On Friday a United Nations helicopter came under attack during a rescue mission, which killed a crew member. An army general also died during the operation, the UN said.

"Due to the risks in the country, on March 8, 2025, the Department of State ordered the departure of non-emergency US government employees from South Sudan," the State Department said on Sunday.

"Armed conflict is ongoing and includes fighting between various political and ethnic groups. Weapons are readily available to the population."

South Sudan, the world's youngest country, ended its five-year civil war in 2018 with the power-sharing agreement between bitter rivals Kiir and Machar.

But the president's allies have accused Machar's forces of fomenting unrest in Nasir County, in Upper Nile State, in league with the so-called White Army, a loose band of armed youths in the region from the same ethnic Nuer community as the vice-president.

Kiir urged calm late Friday and told citizens there would be no return to war, but international observers sounded the alarm.

The UN human rights commission for South Sudan warned on Saturday that the country was seeing an "alarming regression" that threatened to undo years of progress to peace.

The International Crisis Group, a think tank, meanwhile said: "South Sudan is slipping rapidly toward full-blown war."

It warned the country risked "large scale ethnic massacres if the situation is not soon contained".