(Reuters) - On a trip to New York last year, South Sudan's then Vice-President Riek Machar dismissed fears of a military coup in his newborn country, saying such a move would be "unwise".
"We don't want to start a new state with a rebellion," Machar said. A year later, this former bush rebel turned politician is being accused by his former boss President Salva Kiir of attempting just such a power grab in the world's newest state, which split from Sudan two years ago.
This week's fighting in South Sudan, which started in the presidential guard and then spread to other army units and civilians, has quickly followed ethnic fault lines - Kiir is from the dominant Dinka tribe, while Machar is a Nuer.
He was sacked as vice-president by Kiir in July in a cabinet purge aimed at political rivals, reviving the often violent factionalism that has plagued southern Sudanese politics, even during the long North-South civil war.
These political and ethnic splits threaten the future of this fragile oil-producer straddling the great Sudd marshes of the Nile, still new to the ways of democracy and struggling to forge a unified identity out of a patchwork of over 60 often feuding tribes after Africa's longest civil war.
Arguably South Sudan's best-known living politician, British-educated Machar has been an eternal pretender for power in the south in a checkered political career that began two decades ago and even saw him allied for a time with his new nation's old enemy, Muslim-ruled Sudan.
"All politicians are ambitious, and I think he is genuine in his conviction that he can do a better job than Salva Kiir," said Douglas Johnson, a South Sudan expert who knows Machar and has written about the Nuer and their culture.
Ten days before the outbreak of the fighting, which has sent diplomatic envoys scrambling to prevent South Sudan from collapsing into chaos, Machar and others purged by Kiir from the Sudan People's Liberation Movement (SPLM) government in July accused the president of "dictatorial tendencies".
"The SPLM Chairman has completely immobilized the party, abandoned collective leadership and jettisoned all democratic pretensions to decision making," they said in a statement, adding Kiir was leading party and nation towards "the abyss".
Although Machar has denied leading a coup bid, he has made no bones about wanting to see Kiir removed as president.
"He must go, because he can no longer maintain the unity of the people, especially when he kills people like flies and tries to touch off conflicts on an ethnic basis," Machar, in hiding after fleeing Juba, told French broadcaster RFI on Thursday.
In an interview with Al Jazeera, he said government troops on Monday had killed his bodyguards and some of his relatives in a pre-dawn assault on his Juba residence.
Kiir and his ministers insist there was an attempted military coup by Machar, but not everyone believes this.
"I don't think this was a planned uprising," Johnson told Reuters. "It's as likely that Salva Kiir is using the excuse of putting down a coup to suppress political dissent," he added.
Officials say Machar has now been joined by various Nuer allies, including at least one notorious militia leader, former Sudan People's Liberation Army (SPLA) General Peter Gadet, whose troops have taken over the ethnic flashpoint town of Bor in Jonglei state, where Nuer fighters massacred Dinkas in 1991.
"The ethnic dimension is in play and it will be very difficult to roll that back," said one Western diplomat who has long covered South Sudan and knows Machar.
United Nations and African envoys are trying to start up a peace process that will halt the faction fighting, which has already killed at least 500 people, displaced several thousands and spread to vital oil fields. Kiir has said he is ready to sit down to negotiate a settlement with his opponents.
"What is behind it is a power struggle between various groups and personal ambitious by main politicians that we all know," said the diplomat, who asked not to be named.
"There are no good guys in this."
Despite Machar's characterization of Kiir as an autocrat promoting an ethnically-biased "Dinkocracy" in South Sudan's government and military, there are many who doubt whether he himself offers a credible alternative as a national leader.
On the contrary, Machar is widely seen as a divisive figure within the SPLA/SPLM rebel group that now rules South Sudan.
Blamed for the 1991 Bor massacre, he is viewed by many former comrades as a traitor for the 1997 Khartoum peace accord he signed with the Sudanese government, which then rewarded him with the positions of vice-president of Sudan and chairman of the coordinating council that technically ruled the south.
He rejoined the rebel SPLA in 2002, and then after the 2005 peace accord that ended the civil war and established southern autonomy, he became vice-president of the South, maintaining this role after formal independence in 2011, until his sacking.
"He has a very volatile history. I don't think most people in South Sudan could see him as a national leader," said Jok Madut Jok, chairman of South Sudan's Sudd Institute think tank and a former government official.
"He is very ambitious to take the top office in the land, and nothing else matters," he told Reuters.
Johnson said that since the death in a helicopter crash soon after the 2005 peace accord of charismatic SPLA leader John Garang, the movement had struggled to find leaders of national stature to steer the emerging country to stability.
Machar, 61, was educated at Scotland's Strathclyde University and also has a PhD in strategic planning and industry from Bradford University. He had a reputation in the diplomatic and aid community as one of the more open and approachable members of independent South Sudan's government.
This contrasts with Kiir, a blunter former guerrilla commander who spent much of his life in the bush and as president likes to wear wide-brimmed cowboy hats.
In 1991, Machar married a British aid worker, Emma McCune, and their life together in the war-torn south Sudanese bush became the subject of newspaper articles and even a book.
McCune died aged 28 in a car crash in Nairobi in 1993.
In an apparent attempt to bolster his stature as a leader of the Nuer, South Sudan's second largest tribe after the Dinka, Machar has kept in his possession a ceremonial stick once carried by a famous Nuer prophet, Ngundeng Bong.
The "dang" stick, made from the root of a tamarind tree and decorated with copper wire, was looted by British colonial troops early in the last century before being bought and returned to South Sudan in 2009 by British academic Johnson.
"Somehow Riek has managed to hold onto it," said Johnson, although he said this right was contested by some Nuers.
"Intrinsically, it should be something that belongs in a national museum," said the Sudd Institute's Jok. "He kept it for political reasons, and for his own superstitious reasons"
Jok said he did not know whether Machar had managed to take the stick with him when he fled his looted compound in Juba.
"He is a man on the run," he said.
Additional reporting by Edmund Blair and Drazen Jorgic in Nairobi; Editing by Giles Elgood