NAIROBI - Three weeks of fighting in South Sudan between forces loyal to President Salva Kiir and supporters of his rival, deposed vice president Riek Machar, have left thousands of people dead.
Following are the major regional and international players in the conflict.
Khartoum, which fought four decades of civil war with what was once the southern part of Sudan, had said little since the fighting started within the new state of South Sudan. But Sudanese President Omar al-Bashir called for peace as he visited Juba on Monday for talks with Kiir.
Sudan, which long opposed South Sudan's push for independence, has seen that what it predicted all along -- independence marred by ethnic and political divisions -- has materialised in less than three years.
But in the mid- and long-term Khartoum realises it is in its own interests to promote stability in its southern neighbour.
Bashir knows both Kiir and Machar and has been close to both men at different times.
South Sudan, which derives almost all its revenue from oil, has, since it gained independence from Sudan in 2011, been reliant on the north's infrastructure to export its petroleum.
Kenya, Uganda and Ethiopia all have regional leadership ambitions, and are trying to use their influence to end the fighting.
Kenya is the largest single foreign investor in South Sudan. Kenyan nationals flocked there after independence in 2011 to set up businesses.
If South Sudan were to descend into full-blown civil war Kenya, which already hosts more than 400,000 refugees from Somalia, would again be hit by another influx of refugees from South Sudan.
Relations between Sudan and South Sudan have on several occasions recently looked as if they might break down completely. Were that to happen both Kenya and Uganda would see themselves as an alternative export route for South Sudan's oil.
In the first days of the conflict Uganda sent troops into South Sudan, but insisted that their only mission was to evacuate Ugandan nationals and that this was being done with Kiir's approval.
Opposition lawmakers have criticised the fact that Ugandan President Yoweri Museveni did not seek parliamentary approval for the deployment. Some lawmakers have suggested that the troops went beyond evacuating Ugandans to actually supporting Kiir, an allegation denied by Kampala.
In the civil war between Sudan and South Sudan, Museveni sided with the south. He was a personal friend of the late John Garang, the historical leader of the Sudan People's Liberation Movement.
Ethiopia is hosting peace talks between the two factions, which are struggling to get down to substantive issues at peace talks in the Ethiopian capital.
The Horn of Africa country has long seen itself in a regional leadership role.
The United States was instrumental is bringing about South Sudan's independence. It is pressuring Kiir and Machar to overcome their differences and reach a ceasefire agreement, but has also pulled some of its embassy staff out of Juba, sparking speculation it is not optimistic about the outcome of the talks.
China, which has close ties with both Khartoum and Juba, is also trying to broker a truce between the warring factions in South Sudan.
China is a key stakeholder in South Sudan, with heavy investment in the country's oil sector and as a buyer of most of its crude output.
Intergovernmental Authority on Development (IGAD)
This regional body counts among its members Sudan, Ethiopia, Kenya and Uganda. IGAD sent in envoys right from the start of the conflict. The body's member states may have differing agendas, with several states seeing themselves in a regional leadership role, but all are united in their desire for regional stability.
Initially perceived as favourable to Kiir, IGAD is now pushing for Kiir to release the 11 political figures that he rounded up and imprisoned -- a key demand by Machar's delegation, which wants some of the 11 to take part in the talks.
Regional players in the South Sudan crisis