A South Sudan surprise: breakthrough on peace talks? Maybe.

President Salva Kiir and rebel leader Riek Machar are to arrive in Addis Ababa on Friday after five months of bitter fighting. 

Leaders of both sides of South Sudan's bloody five-month civil conflict agreed Tuesday to go to Ethiopia for peace talks this Friday. 

The announcement comes after a week of heavy diplomacy, with visits to South Sudan's capital by UN Secretary-General Ban Ki-moon and US Secretary of State John Kerry, who threatened targeted economic sanctions against the belligerents. After months of a fruitless peace process, there are at least some tentative hopes now for a breakthrough.

The development comes as a surprise, especially in the midst of bitter fighting centered around the northern oil town of Bentiu, which both sides have held at least twice since fighting broke out five months ago. President Salva Kiir and his rival, former Vice President Riek Machar, have been warring since Dec. 15, when their political power struggle turned violent and took on an ethnic bent that has engulfed more than half the nation.

Thousands have been killed, including hundreds of civilians slaughtered in ethnic massacres. More than a million people have fled their homes. On top of what is already a humanitarian disaster, the threat of famine looms if people cannot access fields to plant crops before seasonal rains arrive this month.

Until this week, however, neither Mr. Kiir nor Mr. Machar had made any serious motions toward peace, despite worldwide condemnation of their behavior.

Last Friday, after a visit by Secretary Kerry in which he underscored the legitimacy of the Kiir government -- a shift in the US position -- Kiir agreed to meet Machar face to face in Addis Ababa, Ethiopia's capital. Talks already under way there have been stalled for at least two months.

It first appeared such talks were not going to happen. Sources say Machar was unwilling to attend talks without an agenda. He demanded that Ugandan troops now in South Sudan by the invitation of Kiir withdraw, and asked Kiir to step down.

Kiir himself dashed hopes of talks when, 48 hours after meeting Mr. Kerry, he began a major offensive against the rebels, taking both Bentiu and Nasir, deep in the rebel heartland and near where Machar had been hiding. 

The continued fighting spurred Kerry to forcefully reiterate on Monday the US threat of targeted sanctions against leaders on both sides, which include asset freezes and travel bans. The threats had some effect, apparently, as many of South Sudan’s elite have their main accounts abroad and have relatives living outside the country.

Some skepticism

Today's visit by Mr. Ban at first appeared similarly fruitless. Yet as the UN chief was preparing to leave, he received a call from Machar, during which the rebel leader, who may be on the run after the fall of Nasir, affirmed he would go to Addis Ababa -- a decision taken after he spoke with Ethiopia's prime minister, Hailemariam Desalegn.

Though it appears the efforts of Kerry, Ban, Mr. Desalegn, and others, as well as the ratcheting up of sanctions threats and talk by neighboring countries of military intervention, heightens prospects for a period of calm, there is also much room for skepticism. 

Small skirmishes continued around Bentiu on Tuesday and there were reports of a buildup of troops around the town. Machar has also said that he has little control of some rebel militias who are gunning for revenge against the government supporters.

Moreover, according to Ban, Machar agreed only to go to Addis Ababa and meet with Desalegn. He said the Ethiopian prime minister will have to bring the two leaders together to talk. 

Ban added that Machar may not even make it to Addis by May 9, when Kiir says he will arrive.

“He responded positively that he will be in Addis Ababa for the meeting," Ban said.  "But he said he will try his best because he’s in a very remote area."