South Sudan peacefully broke away from Sudan in 2011 after a brutal civil war and years of effort by U.S. leaders, but since then the country has seen multiple bouts of ethnic violence in Jonglei. The country is awash in weapons many held by civilians and security forces accused of poor discipline.
Watchdog groups have recently noted some rights violations allegedly committed by South Sudan's armed forces as they attempt to quell Yau Yau's rebellion. Many Murle have been killed and others have fled to the bush in recent violence.
Yau Yau, a former colonel in South Sudan's military, first rebelled against Juba after he failed to win a parliamentary seat in the 2010 general elections, accusing the ruling party of rigging the elections. In 2011, he accepted an amnesty offer by President Salva Kiir and returned to Juba. But last year he fled to Khartoum and started a rebellion against Juba in his home region of Pibor.
South Sudan officials accuse Sudan of supporting Yau Yau's rebellion in order to block South Sudan's plans to build an oil pipeline through Ethiopia, charges denied by Khartoum.