Juba (AFP) - US President Barack Obama warned the leaders of South Sudan against a military coup Saturday after four US servicemen were wounded in an attack on their aircraft in the increasingly unstable country.
"Any effort to seize power through the use of military force will result in the end of longstanding support from the United States and the international community," the White House said in a statement.
Obama stressed that the South Sudanese leaders "have a responsibility to support our efforts to secure American personnel and citizens in Juba and Bor," the capital and a rebel-held flashpoint town in the African nation.
The president's comments came after three CV-22 Osprey aircraft came under fire in South Sudan as they headed to Bor to help with efforts to evacuate Americans from the country teetering on the brink of a return to civil war.
The attack damaged the tiltrotor aircraft, forcing them to divert to Uganda. The wounded were then flown to Nairobi for medical treatment and are now in "stable condition," the Pentagon said in a statement.
The attack underlined the increasingly dangerous situation in South Sudan, where at least one UN base has also come under attack in recent days, with the murder of two Indian peacekeepers and possibly dozens of civilians.
The United States, Britain, Kenya and Uganda have been carrying out evacuation missions for their nationals.
Oil companies have flown out their workers after the death of at least five South Sudanese oil workers on Wednesday, with Chinese state oil company China National Petroleum Corp confirming it was pulling out its staff.
Oil production accounts for more than 95 percent of South Sudan's fledgling economy.
The United States has also deployed 45 combat-equipped troops to the country to protect its embassy and personnel.
The hostilities in the poor but oil-rich nation, which won independence from Sudan in 2011, are between troops loyal to President Salva Kiir and forces backing his sacked vice president, Riek Machar.
Kiir accuses Machar of having tried to mount a coup, but Machar denies that and claims Kiir is conducting a violent purge.
At least 500 people have been killed in the capital Juba alone in six days of fighting.
Foreigners evacuated, South Sudanese cower in fear
Tens of thousands have been displaced, many seeking shelter at UN bases amid warnings that the impoverished nation was on the brink of all-out civil war.
"I am afraid. I just can't imagine being forced to become refugees again," said Susan Nakiden, a South Sudanese woman among the thousands sheltering at a UN base in Juba. The mother of three said she had already been forced to flee her home during the civil war with Sudan.
Local resident John Luga said people were living in fear, whatever their clan.
"Whether they are Nuers or Dinkas, the suffering is for all, the future is not certain," he told AFP.
South Sudan's embattled government, meanwhile, said a top army commander in the northern Unity State, Major General James Koang Choul, had defected to Machar's fast-growing rebel force.
"We have lost contact with the commander... and there are reports he has joined the forces of Riek Machar," Sudan People's Liberation Army spokesman Philip Aguer told AFP.
Army seeks to take back Bor
Aguer also insisted that government forces were in control of area around Bor, some 200 kilometres (125 miles) north of Juba, and an army operation was underway to take back the town seized by rebels this week.
"There is fighting, but we are supported by air units," he said.
Although the unrest appeared to start as a result of a political spat, the violence has taken on an ethnic dimension pitting Kiir's ethnic Dinkas against Nuers, to which Machar belongs.
South Sudan gained independence from Sudan as part of a peace process after a two-decade civil war that left two million dead, but it has never been able to heal its own ethnic rivalries.
US Secretary of State John Kerry underlined Obama's message in a call to Kiir, telling him the conflict was threatening South Sudan's hard-won independence that was backed by the United States.
Kerry has dispatched his special envoy for Sudan and South Sudan, Donald Booth, to the region to encourage talks between the warring factions.
African ministers have also stepped up pressure on Kiir to start talks with Machar.
United Nations Secretary-General Ban Ki-moon has called for an end to hostilities and urged the leaders of Sudan's warring factions "to resolve their personal differences through dialogue immediately."