A man holds South Sudan's national flag during the country's fourth independence day celebrations on July 9, 2015 at John Garang Mausoleum grounds in Juba. The world's youngest nation South Sudan marks four years of independence on July 9, after separating from old foe Sudan following decades of war. A civil war in the new country broke out on December 2013 and the UN says South Sudan now ranks "lower in terms of human development than just about every other place on earth". AFP PHOTO / CHARLES LOMODONG        (Photo credit should read CHARLES LOMODONG/AFP/Getty Images)