South Sudan unrest explained - in 60 seconds
23 December 2013 Last updated at 23:02 GMT
More than 500 people are believed to have died in clashes in South Sudan between rival army factions.
President Salva Kiir says it was a coup attempt, blaming soldiers loyal to former vice-president Riek Machar for the trouble, but he denies this.
South Sudan analyst James Copnall investigates the historic enmities threatening to tear apart the world's newest country.