The president of Sudan has met his South Sudan counterpart and declared that 20 years of war between their countries showed that negotiations are the only way forward for the region.
After decades of war, South Sudan peacefully broke away from Sudan in 2011. The two countries remain bound together by their shared oil industry. South Sudan has most of the region's oil but it must pump it through pipelines that run through Sudan. The outbreak of fighting is costing Sudan lost oil revenue.
South Sudan has seen three weeks of violence that Mr Kiir says began as a coup attempt, although Mr Machar's side denies the allegation. Violence began as a political dispute but has since taken on ethnic dimensions, with tribes attacking each other.
The fighting has forced an estimated 200,000 people to flee their homes in search of safety. More than 1,000 people have died. Forces loyal to Machar have been in control of two important state capitals.
They control the town of Bentiu, the capital of oil-rich Unity State. The south's government has said oil is no longer flowing from Unity's fields. Most, if not all, of the Chinese and Pakistani oil workers have left the country because of the outbreak of violence.