South Sudan crisis explained - Telegraph Who is fighting who? The two protagonists are Salva Kiir, the president of South Sudan, and Riek Machar, who was sacked as vice-president in July. These men have been struggling for power for some time. Behind their rivalry lies ethnic antagonism: Mr Kiir is a Dinka, the largest tribe in South Sudan, and Mr Machar is a Nuer. What triggered the bloodshed? The fighting began in the capital, Juba, on Sunday. That is just about the only agreed fact in this episode. Mr Kiir says that military units were attacked across Juba, heralding the start of an attempted coup. He claims to have thwarted a bid by Mr Machar to seize power. However, the former vice-president disputes this version of events. He says there was no coup and the initial clashes were caused by a "misunderstanding" within the Presidential Guard. Mr Machar says the situation escalated when he and his followers were deliberately attacked. He says this came in retaliation for his criticism of Mr Kiir's increasingly dictatorial rule. How serious is the fighting? Serious enough to have forced a general evacuation of foreign nationals from Juba. Britain and America have both withdrawn all non-essential staff from their respective embassies and urged all their citizens to leave South Sudan immediately. A C-17 transport plane from the RAF, capable of carrying 300 passengers, landed in Juba on Thursday with the aim of evacuating any British nationals. No-one knows how many people have died in the fighting in the capital, but about 500 is the most common estimate. Didn't South Sudan recently achieve independence? Yes - this is the world's newest nation. South Sudan was born in July 2011, breaking away from Sudan after a five-decade struggle against rule by Khartoum. That long war between the Arab Muslim north and the black African south claimed about two million lives. The outcome was that the Sudan People's Liberation Army (SPLA), which led the struggle against Khartoum, then took power in the new country. Guerrillas are not generally good at building states and running governments - and so it has proved in South Sudan. Critics say that Mr Kiir runs a militarised, autocratic and corrupt administration which has failed at the task of state-building. What is the worst case scenario? A new civil war with ethnic overtones, pitting the Dinka against the Nuer. Already, there are reports of targeted killings, with Mr Kiir's forces allegedly singling out Nuers for interrogation or worse. Meanwhile, Mr Machar's soldiers appear to have taken control of Jonglei state, north of Juba. Mr Machar himself is hiding in an undisclosed location. He has almost certainly left Juba, possibly for Jonglei. How might the worst be avoided? International mediation is the only answer. Left to themselves, Mr Kiir and Mr Machar would probably fight it out. A diplomatic effort to settle this conflict is likely to be launched. If so, this will probably be led by America, Britain and Norway - the three powers who are the official guarantors of the peace agreement that led to South Sudan's secession. African countries - particularly Kenya, Uganda and Ethiopia - will also be a key part of this effort.