By Nicholas Kulish/New York Times
JUBA, South Sudan — Rebel forces attacked the South Sudanese city of Bor on Tuesday, engaging in fierce fighting with government forces over the city, a strategic location seen as a gateway to Juba, the capital.
But as the fighting raged, there were indications that talks to end the conflict would soon be convened in Ethiopia. “The current information we have is that both sides are coming,” said Dina Mufti, a spokesman for the Ethiopian Foreign Ministry. “We are expecting the arrival of both delegations, perhaps today.”
South Sudan’s foreign minister, Barnaba Marial Benjamin, told Reuters that the government would take part. “We are going there,” the agency quoted him as saying. As for the rebels, the BBC reported that their leader, Riek Machar, said he would join the talks.
Leaders of several East African nations have been pressing Salva Kiir, the president of South Sudan, and Mr. Machar, the former vice president, to halt the conflict, and at least one leader threatened to intervene if the two sides did not begin peace talks by Tuesday.
It was not clear how countries like Kenya, Ethiopia and Uganda would respond to the fighting in Bor. President Yoweri Museveni of Uganda called on Monday for nations in the region to to “defeat” the rebel forces if they did not agree to a cease-fire.
A spokesman for the United Nations Mission in South Sudan said on Tuesday that the rebels had captured an airstrip on the outskirts of Bor and a key crossroads leading to Juba.
“Our people were hearing tank fire, rockets and small-arms fire,” said Joseph Contreras, the spokesman. “The latest reports that I have are that the antigovernment forces are in control of the area on the southeastern outskirts where our facility is located,” he said, referring to a United Nations compound there.
The rebels controlled the city early in the revolt, but were dislodged last week. They returned in stronger numbers, with renegade military units backed by the armed youth known as the White Army.
“It began this morning at around 7,” said Col. Philip Aguer, a South Sudanese military spokesman. “It’s heavy. It’s very intense fighting.”
For several days, groups including the United Nations warned that large numbers of fighters were advancing toward Bor, the capital of Jonglei State.
Thousands of civilians have left the United Nations compound in Bor, some bound for Juba and others crossing a river into a neighboring state. Mr. Contreras said that by the time the fighting broke out Tuesday morning, there were around 9,000 people sheltering at the camp, down from a peak of around 17,000.
“All of our staff are safe and sound, according to the last reports we received,” Mr. Contreras said. “We have no reason to suspect or fear any kind of assault on our facility or attacks on out staff at this time.”
The fighting began on Dec. 15 after Mr. Kiir, who dismissed Mr. Machar in July, accused Mr. Machar of attempting a coup. Mr. Machar has denied the accusation. More than 1,000 people have been killed in clashes since then, including large numbers of civilians, and close to 180,000 people have been displaced over the two weeks of conflict.
United Nations peacekeepers have had a difficult time trying to protect civilians; on Dec. 19, around 2,000 armed youths overran a United Nations base in the town of Akobo, killing at least 11 civilians who had sought refuge there and two peacekeepers.
Mr. Museveni of Uganda has been outspoken in calling for concerted regional action to halt the conflict. “We gave Riek Machar four days to respond, and if he doesn’t, we shall have to go for him, all of us — that is what we agreed in Nairobi,” Mr. Museveni told reporters on Monday, referring to a meeting of East African leaders in the Kenyan capital last week.
That raised the prospect of an escalation or even cross-border spillover, adding to a worrying picture for a region already suffering from bloodshed in the Central African Republic and the Democratic Republic of Congo.
Mr. Museveni and Mr. Kiir have been close for years, and the Uganda People’s Defense Force provided significant support to the Sudan People’s Liberation Army during the civil war against the Sudanese government in Khartoum, analysts said.
“The U.P.D.F. has always been a very good friend of the S.P.L.A.,” said Mareike Schomerus, a researcher on South Sudan at the London School of Economics. “Some would say without U.P.D.F. the S.P.L.A. would never have been able to fight the war in that way.”
Mr. Machar has said Ugandan aircraft have bombed rebel positions, an assertion Uganda has denied.
“That remains speculative, and I have no idea that we’ve engaged in such an action at all,” said Lt. Col. Paddy Ankunda, a spokesman for the Ugandan military. “But our briefing is very clear. Should we be attacked, our soldiers have a right to defend themselves.”
There have been conflicting reports about the size of the White Army force, called that because of the white ash that fighters rub onto their skin. South Sudan’s information minister said last week that 25,000 Nuer youths had been mobilized; others have put the number at a few thousand, saying that elders from their community had persuaded many to turn back.
“They are using big numbers we can’t estimate,” Colonel Aguer said. “But the S.P.L.A. is committed to defend the area.” The advance of the rebel forces sent civilians fleeing across the White Nile by the thousands as fighters burned homes in their path. The Nuer fighters were carrying AK-47’s and had several heavy machine guns and 30 vehicles and trucks, according to the South Sudanese military.
Colonel Aguer said that the S.P.L.A. had a brigade in and around Bor and more forces between Juba and Bor who could be sent in as reinforcements.
Bor appeared to be the epicenter of the violence on Tuesday. Malakal, the capital of Upper Nile State, where the two sides have clashed in recent days, was calm and under the control of the military. Bentiu, the capital of Unity State, was also peaceful but under rebel control.
The question is what kind of casualties might occur if the South Sudanese Army, alone or with assistance, tried to retake places like Bentiu that are in rebel hands. The fight for Bor could turn particularly nasty, with neither side wanting to give up such a prize. The city is a few hours’ drive north of Juba.
“Regional armies need to assure that their use of force stays firmly within international law, and that civilians are under no circumstances targeted,” Ms. Schomerus said. “It is right now unclear which actors are committing what kind of atrocities — but what is already clear is that civilians are not being sufficiently protected by anybody, and quite possibly even targeted.”