After months of war, it took a brutal massacre followed by a revenge attack inside a UN compound to bring international attention back to a country racked by both violence and a deepening humanitarian crisis.
South Sudan’s downward path is now being talked about in the context of the two great African disasters of a generation – the famine in Ethiopia and the genocide in Rwanda.
The UN says “crimes against humanity” are being carried out, and the mass killing has been described as “a game-changer”.
But what can be done to stem the violence and bring peace to the world’s youngest country?
A rush of international diplomacy has begun.
First came a high level UN human rights delegation, which will be followed by US Secretary of State John Kerry’s visit on Friday, and a regional leaders’ summit in the capital, Juba, this weekend.
Talks in neighbouring Ethiopia have failed to make progress towards a peace deal, and neither side has honoured a ceasefire agreed in January.
The pressure is now being piled on President Salva Kiir and former vice-president turned rebel leader Riek Machar to agree an end to the violence.
The ethnic nature of what began as a political crisis is most worrying.
‘Verge of catastrophe’
The two men lead the country’s two biggest ethnic groups – the president’s Dinka community and Mr Machar’s Nuers – the split has sparked a continuous cycle of revenge killings, which is racing out of control.
Bodies have been lying in the streets of Bentiu for two weeks – since Nuer rebel forces re-took the town from pro-government troops.
The UN said hundreds of non-Nuers were killed and has alleged hate speech was broadcast on the radio to incite ethnic violence.
There are also reports of moderate Nuers being killed – another eerie hark-back to Rwanda 20 years ago.
Survivors described a massacre in a mosque – where civilians had taken shelter from the fighting – others were killed in a church.
Aid organisation Medecins Sans Frontieres said at least 33 people were killed in the state hospital, and they have treated 230 people for gunshot wounds.
The brutality of the killing sparked a reaction in Bor – a flashpoint town currently held by the government.
A Dinka mob attacked the UN compound in what appears to have been a well-organised attack – 46 people under UN protection died, along with a dozen attackers.
The UN High Commissioner for Human Rights, Navi Pillay, used strong words, saying “crimes against humanity” were being carried out in South Sudan.
Meeting both leaders, she stressed they would be held accountable for the actions of their followers, describing the crisis as: “A personal power struggle that has brought their people to the verge of catastrophe.
“They must stop blindly dragging their people down the path of self-destruction.”
There will be a similar message from Mr Kerry who has begun his trip in Ethiopia’s capital, Addis Ababa, where he is urging progress from peace talks which resumed this week.
The US was pivotal in South Sudan gaining independence, so its opinion holds sway.
Sanctions on individuals have become a popular international tool of pressure at the moment, but it is not certain if Mr Kerry will go that far.
Presidents Barack Obama and Kiir got off to an uneasy start, and the latter has recently spoken against Western interference and the need for African solutions to African problems.
It is a view supported by regional heads of state who will hold a mini-summit in Juba on Saturday, but they are expected to further pressure President Kiir.
Foreign diplomats watching the situation closely warn the next month will be a dangerous time before three battalions of UN peacekeeping troops can deploy, with broader rules of engagement – as recommended by UN chief Ban Ki-moon in March.
The 2,500 soldiers from Ethiopia, Kenya and Rwanda would be allowed to use greater force to keep the two sides apart and protect civilians.
Regional agreement for this seems close, but waiting for approval from the UN Security Council and the time it takes for logistics will leave a vacuum, where the incentive is not to stop fighting, but to ensure more ground is captured or held.
Fear of famine
The cycle of ethic-based killing and revenge attacks is spreading and even if the two leaders committed to peace, at some point the violence may become impossible to stop.
Fighting may soon return to Bentiu as pro-government troops prepare to re-take the town from rebels.
There is the fear the troops will be bent on revenge after the massacre.
Four thousand mainly Nuer people have arrived at the UN compound in the city in the last few days, taking the total number sheltering there up to 27,000.
Across the country 80,000 people are under UN protection, but conditions in the camps are poor as the rainy season hits sanitation and makes life increasingly miserable.
With 1.2 million people displaced and the UN estimating 4.9 million in need of humanitarian assistance, the fear of famine later in the year appears justified.
If crops are not planted, a far more serious situation could emerge in the months ahead.
The pressure is on the president – and the rebel leader – to at least engage more seriously in a peace deal.
But with both sides continuing to blame each other, the prognosis for South Sudan continues to be poor.