South Sudan, the world's newest country, is in political limbo after rebel leader and former vice president Riek Machar fled earlier this week. His whereabouts remained unclear Saturday after a spokesman for Machar and the United Nations both said he was in neighboring Congo but Congo's government said it had no knowledge of him being there. His departure puts South Sudan's peace deal, reached a year ago under international pressure, into disarray while the country's humanitarian crisis worsens.

WHY THERE IS CHAOS IN JUBA

Machar and many of his supporters fled the capital after last month's fighting between government and rebel forces, in which hundreds of civilians were killed and fears grew of a return to civil war. The fighting displaced at least 15,000 people in the capital. About 12,500 fled to U.N. camps in Juba, where food remains scarce. Witnesses told The Associated Press that soldiers in government army uniforms raped women who ventured outside the camps to collect food, as U.N. peacekeepers stood by. After he fled, Machar was replaced as first vice president, a post he held for just a few months under the fragile peace deal. He has been replaced by another official in his party, Taban Deng, but that appointment has not been accepted by many of Machar's supporters. A spokesman for Machar's opposition SPLM-IO party, Mabior Garang, told AP that the move was "illegal" and claimed that some officials who nominated Taban were "coerced by security officials."

MACHAR HAS VANISHED, BUT THAT COULD HELP HIM

Taban has pledged to step down if Machar returns to the capital. Machar says he will return to Juba only after a regional peacekeeping force arrives and secures Juba. Last week, the U.N. Security Council voted to send 4,000 additional peacekeepers to South Sudan with a strengthened mandate to provide security. President Salva Kiir's government at first rejected the decision, saying it violated the country's sovereignty. But in recent days, the government has been more receptive to the U.N. plan. Machar's flight from South Sudan could give him more visibility and increase pressure on the international community to send in the regional peacekeepers.

HOW MACHAR'S FLIGHT COULD SPARK NEW ETHNIC VIOLENCE

Most South Sudanese who are Dinka, the largest ethnic group of South Sudan's 12.5 million people, support their tribesman, President Kiir. Most ethnic Nuer, the second largest group, support Machar's opposition party, with some notable exceptions. There has been sporadic fighting in parts of the country since Machar and his forces fled, especially in the south. Local and opposition officials in the Yei region say clashes have taken place there. The region had little violence during the country's civil war, which began in December 2013. The fighting in Yei indicates that violence has shifted to a new front following Machar's disappearance.

SOUTH SUDAN'S HUNGRY ARE FLEEING BY THE THOUSANDS

The displaced are not just in Juba. There are 190,000 South Sudanese living at U.N. camps across the country. At these sites, U.N. peacekeepers have been criticized for failing to protect civilians. About 70,000 South Sudanese have crossed the border into Uganda since the July clashes, adding to the more than 2.3 million people who have been displaced both inside and outside the country since the civil war began, according to the U.N. The new refugees have overwhelmed humanitarian agencies that are already short on funding. Earlier this week, the U.N. said it was forced to cut food assistance in half for 200,000 South Sudanese in Uganda. "Never has the gap between what is being provided and what is needed been larger," said acting UNHCR Representative to Uganda Bornwell Kantande.