Fighting broke out in South Sudanese capital Juba earlier in the week, and while that conflict has settled, violence is escalating in other parts of the country.
Hundreds of people have died in violent clashes throughout South Sudan, which gained independence from Sudan in 2011 after more than two decades of brutal civil war.
US Secretary of State John Kerry said he is sending a special envoy to South Sudan to help foster dialogue between opposing factions in the violence-wracked nation.
"Now is the time for South Sudan's leaders to rein in armed groups under their control, immediately cease attacks on civilians, and end the chain of retributive violence between different ethnic and political groups," Kerry said, as he announced plans to dispatch Ambassador Donald Booth, his special envoy for Sudan and South Sudan, to the region on Friday.
The US has deployed 45 troops to the violence-wracked country to protect US personnel and interests.
US Secretary of State John Kerry said Friday he was sending a special envoy to South Sudan to help foster dialogue between opposing factions in the violence-wracked nation.
President Barack Obama earlier called for an immediate end to the fighting in South Sudan, warning the country stands at the "precipice" of civil war.
Obama warned that "recent fighting threatens to plunge South Sudan back into the dark days of its past."
He made his remarks in a strongly-worded statement, his most pointed remarks to date on the bloodshed in the nascent African nation.
The growing violence has prompted fears that the world's youngest nation could slide toward civil war.
"Fighting to settle political scores or to destabilize the government must stop immediately. Inflammatory rhetoric and targeted violence must cease," the president added in his statement.
"All sides must listen to the wise counsel of their neighbors, commit to dialogue and take immediate steps to urge calm and support reconciliation.
"South Sudan's leaders must recognize that compromise with one's political enemy is difficult; but recovering from unchecked violence and unleashed hatred will prove much harder."
On Tuesday, the United States ordered all non-emergency embassy staff to leave South Sudan and stressed that the onus to end the violence was on the country's leaders.
The US mission in the capital Juba also has suspended normal operations for the time being.
In an example of the danger facing foreign troops in the volatile country, three Indian peacekeepers were killed Thursday in an attack by ethnic Nuer youths on a United Nations base in Jonglei state. Other casualties are feared.
Recalling the promise and hopes that accompanied South Sudan's entrance into the community of nations just two years ago and Juba's progress in mitigating violence, Obama warned that "today, that future is at risk."
"South Sudan stands at the precipice," the president said, promising that the United States would remain a "steady partner" of the fledgling nation.
"South Sudan has a choice," he continued. "Its leaders can end the violence and work to resolve tensions peacefully and democratically."
Foreign Minister Bishop urges Aussies to leave South Sudan
Foreign Minister Julie Bishop said the situation was "exceptionally volatile", and recommended any Australians who had not yet left to do so as soon as possible.
"I am aware there are a number of Australians who remain in South Sudan. However, I have not received any reports from local authorities of any Australians being injured as a result of the violence," Ms Bishop said in a statement.
The Department of Foreign Affairs and Trade told SBS yesterday there were at least 96 Australian citizens in South Sudan, including 58 in the capital Juba.
The US and UK have sent assistance to help evacuate their citizens from South Sudan, but there are concerns that Australian citizens have been left without similar assistance.
An Australian-South Sudanese man, Daniel John Barak, in Juba has told SBS the Australian government is not doing enough to help its citizens stranded in the country.
DFAT says it has not had reports from Australians saying they are stranded in South Sudan.
"We are, through our High Commission in Nairobi, organising for daily welfare checks of the Australians in the country," says DFAT spokesman Justin Brown.
"We've done mass mailouts of our updated travel advice. We have a smartraveler travel advice (website) which has been updated twice in the last couple of days in light of developments. And we're using those sorts of tools and relationships with our consular counterparts to maintain contact with the Australians in the country."
Juba airport remained open, but if it was not safe for people to depart, Ms Bishop recommended they stayed indoors and ensured food supplies were well stocked.
The Department of Foreign Affairs and Trade has updated its travel advice three times since December 16, and advises Australians not to travel to South Sudan.
