U.S. Secretary of State John Kerry is in Juba for talks on how to end deadly fighting that threatens to send South Sudan into a civil war.
Kerry met for more than an hour Friday with President Salva Kiir. Later, he plans to speak by telephone to ex-vice president and current rebel leader Riek Machar.
The top U.S. diplomat is trying to arrange face-to-face talks next week between both men, a meeting he called "critical" in efforts to end hostilities and to discuss a transition government.
On Thursday, Kerry blamed the violence on a rivalry between both leaders. He said both need to condemn brutal attacks against innocent people.
Kerry is also trying to negotiate a deal to send African Union peacekeepers as soon as possible to help stop the fighting and protect civilians.
The worst violence started in December when Mr. Kiir accused Machar of trying to attempt a coup. Much of the violence has fallen along ethnic lines.
Thousands of people are believed to have been killed and more than one million displaced as a result of the violence in the world's newest country.
The U.S. has threatened sanctions against those responsible for the violence, including Mr. Kiir and Machar.
Kerry is on a multi-nation tour of Africa that has largely focused on security and human rights issues.
While in the Ethiopian capital Thursday, Kerry said the United States supports African-led efforts to combat "the most deadly conflicts of the continent." He said too many nations are at risk of descending into broad-based violence.
"It is clear that the unspeakable violence in the Central African Republic, the deliberate killing of civilians on both sides in South Sudan, both of those underscore the urgency of the work that we have to do together."
On Thursday, Kerry held talks with AU officials on the Central African Republic where Muslims continue to flee their homes to escape attacks by Christian militia.
After returning to Addis Ababa, Kerry is due to meet with Somali President Hassan Sheikh Mohamud to discuss the fight against the al-Qaida-linked militant group al-Shabab.
On Saturday, he travels to the Democratic Republic of Congo's capital to meet with President Joseph Kabila. The two will discuss recent security gains against rebel groups in volatile eastern Congo.
After a stop in Angola, Kerry returns to Washington on Monday.