Things are spiraling downward in South Sudan, one of four nations where, according to the U.N., the greatest humanitarian crisis since 1945 is unfolding. And in the case of South Sudan, it's not drought or climate change that's causing the catastrophe. It's civil war. Last month the U.N. declared a famine in two parts of the country and warned that nearly half the population is in urgent need of food assistance. Soon after this declaration, the American relief agency Samaritan's Purse was forced to pull most of its staff out of one of the famine-stricken zones because of fighting in the area. A skeleton crew of 7 local staff members remained behind. Then on Sunday, armed gunmen abducted those workers. A spokesman for the South Sudanese military said the aid workers were being held for ransom by rebel fighters demanding food aid in exchange for their release. On Tuesday, Samaritan's Purse confirmed that their employees had been let go. "At the very moment that we are talking they are in