The fractious relationship between South Sudan's President Salva Kiir and his former deputy Riek Machar was bound to come to a head.
"You can't have a president and vice president who don't speak to one another. They hate each other, and this situation can't last," a senior western diplomat used to stress when asked about the biggest issues facing South Sudan, the world's newest country.
But no one predicted the break would be so bloody and dramatic. A spat between rival ethnic groups in the presidential guard on December 15 led to a fatigue-clad Kiir denouncing his rival Machar on state TV. Four days later, senior UN figures began warning of a potential civil war.
There is a rebellion against Salva Kiir in the SPLA. The SPLA are fed up with Salva Kiir and want him out.
Calling him a "prophet of doom", Kiir claimed that Machar had tried to seize power through violence after a night of deadly clashes by soldiers trying to storm a military barracks, with tank and mortar rounds rocking the capital Juba.
Hours later, soldiers were surrounding the homes of leading politicians, including 11 former ministers who have been arrested.
Speaking to Al Jazeera from a secret location, the South Sudanese government's most sought-after man says he barely escaped with his life before dawn on Monday, after soldiers from the South Sudanese army came to destroy his home and those inside.
"My bodyguards at the vice presidential residence were summarily executed," Machar claimed. "They attacked it with tank shells and then burned. It is rubble now. They fired on my residence and I fled," adding that some of his relatives were also killed.
"My life was in danger; my colleagues were being arrested for no reason. They are not plotters, it was not a coup. Nobody wants that," he added, claiming he was "used as a scapegoat" by Kiir to purge the ruling SPLM party of rivals to avoid reforming it.
But the roundups have sparked wider conflict in a country whose whole identity is forged in violence - with the legacy of five decades of civil war that pitted rival communities against one another. "The scenario many feared but dared not contemplate looks frighteningly possible: South Sudan, the world's newest state, is now arguably on the cusp of a civil war," said the International Crisis Group (ICG).
According to UN estimates, around 500 people have been killed and 800 wounded in clashes that started in Juba but have spread to military barracks in three other states. "The violence is turning tribal and they are killing people in Juba," said Machar, who hails from the country's second-largest ethnic group, the Nuer.
He said that soldiers were rising up from his native Jonglei state and taking on the majority Dinka, the ethnic group that Kiir and many other leading South Sudanese players come from. Their dominance has led some to dub the nation's political system a "Dinkocracy". Ethnic tensions - usually inflamed by scarce services and resources in an oil-rich but highly corrupt country - can often escalate into inter-communal raids and massacres that leave thousands dead each year.
A few shots fired between different ethnicities in the army have stoked wider grievances among the army and civilians alike. Former undersecretary of culture Jok Madut Jok has warned that the violence could "escalate into tragic acts of ethnic cleansing".
"Some really heart-wrenching acts have already occurred where Nuer soldiers have been attacked and killed, Nuer government officials, even those serving in the offices of Nuer ministers, and ordinary citizens suspected of having participated in the fight against the government," he said. At Nairobi airport in Kenya, those who have fled the violence speak of "door-to-door executions of Nuer" in Juba, despite a calming of Wednesday's fighting in the capital.
'Ethnically targeted violence'
Others say tanks are flattening Nuer villages, members of the country's national intelligence services are picking people off and carting bodies round the capital, and eyewitnesses report executions in busy streets in broad daylight. "Ethnically targeted violence is ongoing in Juba with reports of killings and arbitrary detentions of Nuer civilians," said ICG analyst Casie Copeland.
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What started as a complicated love-hate relationship between two men has now forced thousands from their homes, with more than 20,000 people sheltering at two United Nations bases in the capital and thousands more at bases elsewhere in the country. "Civilians sheltering in [the UN mission in South Sudan] in Juba do not feel secure enough to leave and state that they are targets for violence due to their ethnicity," said Copeland.
On Wednesday, church leaders urged peace as the power struggle spiralled out of control. "There is a political problem between leaders within the SPLM. This should not be turned into an ethnic problem. Sadly, on the ground it is developing into tribalism. This must be defused urgently before it spreads," they said in a joint statement.
Machar accused his former boss of "inciting ethnic killings and tribal divisions," claiming that Kiir was no longer South Sudan's "legitimate leader".
"[He] is covering for his inefficiency in running the government and the army," Machar charged.
Meanwhile, Kiir released a statement to press saying that he would "sit down with Riek".
"We will talk, but I don't know what the result will be," he said, while on local radio he added that Machar had "lost his chance to be president because he has caused this war".
The two men's long history spans of an almost 50-year civil war that saw Machar break away from the SPLA rebel movement in the 1990s. With a force comprised largely of his fellow ethnic Nuers, his forces carried out brutal attacks even on his own people.
A 1991 attack on Dinkas in the city of Bor, capital of Jonglei state, is one of the bloodiest moments in the region's recent history. Machar has struggled to live down the attack, persistently denying claims that he accepted support from the enemy Khartoum.
Now, history is repeating itself in Bor, as a Nuer militia headed by Peter Gadet - a rebel leader who has flitted between the army and warlordism for years - took over the barracks there and in other major towns.
Civil war possible
Machar would not confirm or deny whether he was backing Gadet, only saying that "the rebels are acting in the right direction". But Jok says that he is thought to have headed that way, and that an alliance between the two men and the former governor of Unity state, who is also missing, could be catastrophic.
"If the SPLA engages Gadet and possibly Riek and Taban, then we have an all-out civil war in South Sudan, a mere two years after independence, and making good all the predictions by outsiders that South Sudanese will have limited capacity to build a peaceful nation," wrote Jok on social media.
|Thousands seek refuge from violence in South Sudan
ICG analyst Casie Copeland said that since Sunday, fighting had erupted in five of South Sudan's ten states, while Machar claimed that soldiers were rising up across the land. "There are desertions in division two and in many other areas. There is a rebellion against Salva Kiir in the SPLA. The SPLA are fed up with Salva Kiir and want him out," says Machar.
Unlike his gruff and mumbling nemesis Kiir, Machar has a reputation for being a smooth-talking, wily negotiator. He has a PhD from a British university and married a British aid worker who died in a car crash when he was still a bush commander, before rising to become vice president.
"Sounds of gunfight, traversed with heart-shaking mortar and tank blasts, and which have continued sporadically well into today Wednesday morning, have all spread fear in the population, leaving them hostage to the madness of a few power-hungry men," Jok said.
The government has been quick to point out that Juba is now under their control, while Jok says the uncertainty centres on "the fate of political stability in the whole country" that has paid off many militias for peace.
A security analyst who spoke on condition of anonymity said that the worst-case scenario was ethnic violence taking place in South Sudan's periphery. "And we're at that stage now," the analyst said.
Meanwhile, the ICG said: "Armed groups have at the same time targeted civilians based on ethnicity. Violence has spread beyond the capital, including to areas already fraught with ethnic tensions, principally Jonglei state, over which the government may have lost control.
"Even if a cessation of violence can be achieved and political dialogue established, the SPLA's re-opened wounds will be difficult to heal: if the fighting continues, that split will widen and engulf the entire county in a renewed war," it concluded.