A portrait of turmoil in South Sudan, from behind the lens

South Sudan, the world’s newest country, is again on the brink of a civil war. Photographer Sebastian Rich has covered the conflict in the country for more than four decades, and he is there now on a mission with UNICEF, documenting the turmoil and the toll it has taken on civilians. The area is plagued by malnutrition and the lowest education levels in the world. John Yang speaks with Rich.