South Sudan became independent in July 2011 after waging a five-decade war against the north in what was Africa's longest running civil war. But secession has brought neither peace, stability nor prosperity, despite the country's vast oil wealth. Hostilities with its northern neighbour leave the two countries teetering on the brink of war, and ethnic clashes and rivalries between southern tribes have left many thousands dead.Zeinab Badawi speaks to the UN head of mission for South Sudan, Hilde Johnson. Is the country effectively already a failed state?(Image: Victims of ethnic violence in Jonglei, South Sudan. Credit: Associated Press)