Ethiopia is playing a leading role in trying to get the two sides to negotiate a peace deal. But those efforts have been overshadowed by continuing violence in parts of South Sudan, which has been hit by unrest since mid-December.
President Salva Kiir on Wednesday declared a state of emergency in Unity and Jonglei, two states where rebels loyal to former Vice President Riek Machar control the capitals.
The fighting has exposed ethnic rivalry between the country's two largest ethnic groups, the Dinka of Kiir and the Nuer of Machar. The United Nations says there is mounting evidence that people were targeted for their ethnicity.