Rebel forces vow to take back their stronghold of Lasu in Equatoria State regardless of the ceasefire.
As South Sudan's warring parties haggled over a ceasefire deal this week, dozens of refugees streamed into neighbouring Democratic Republic of Congo, fleeing what they said was a fresh government offensive.
The apparent push to recapture the key rebel stronghold of Lasu came as mediators tabled a ceasefire agreement in Addis Ababa, which was signed by major parties to the four year conflict on Thursday and is to go into force on December 24.
However, with South Sudanese rebel forces vowing to take back their stronghold of Lasu in Central Equatoria State — regardless of the ceasefire — the fragility of the deal was thrown into stark relief.
"I'm not sure the government wants peace. If they wanted peace, why would they attack Lasu so that we have to run again with our children," said Betty Moriba, a 28-year-old mother of five.
Having fled violence twice before, Moriba grabbed her children at the first sound of gunfire and ran towards the DRC, but was unable to salvage any of the family's prized possessions.
She and other witnesses say President Salva Kiir's troops attacked Lasu on Sunday, which has served as the headquarters for the Riek Machar's SPLA-IO, the main opposition movement in South Sudan.
"They came with armoured vehicles and machine-gun-mounted pick up trucks," SPLA-IO spokesman Lam Paul Gabriel told AFP over the phone from Kampala.
Gabriel said the two sides fought each other for several hours on Monday morning before the rebels withdrew. He has vowed to launch a counter-offensive if government forces do not pull out.
Army spokesman Santo Domic Chol denied troops had launched an offensive on the town, accusing the rebels of attacking a government position as well as looting a village for food — forcing troops to step in to save civilians.
"We have been ordered not to engage hostilities by pursuing rebels (but) at times we will fight if we are attacked in our positions which is what happened in Lasu."
However it was unclear what government position he was referring to — as both civilians and an official document released earlier this month indicated the area was under rebel control.
"These government soldiers came from Yei and they were shooting guns and killing people. That's what made us come this way," said James Mana, one of the fresh arrivals in the DRC, near the town of Aba.
Congolese authorities registered more than 200 refugees in the last five days.
Smoke could be seen rising from a village across the border.
'Cost and consequences'
South Sudan this month entered into its fifth year of a war that has killed tens of thousands of people and driven nearly four million from their homes.
The UN Security Council warned last week that there would be "cost and consequences" for any side who blocks "last chance" peace efforts mediated by the regional authority IGAD, in a bid to revitalise a shattered peace agreement.
The peace deal was signed in 2015 to end 21 months of civil war between Kiir's government and Machar's rebels which broke out just two years after independence in 2011.
However the deal effectively collapsed in July 2016, when fresh fighting in the capital Juba forced then-first vice president Machar out of the country and his supporters back to battling the government in the bush.
Violence spread to the southern region of Equatoria, forcing over a million people to flock to neighbouring Uganda and the DRC in what has become the biggest refugee crisis on the continent.
In addition to Kiir's government and Machar's SPLA-IO, this round of peace talks also includes half a dozen armed opposition groups that have sprung up since July 2016, a factor that is likely to further complicate negotiations.
A permanent ceasefire is the first step in negotiations to include a "revised and realistic" timeline to holding elections.
However after numerous failed ceasefires and collapsed peace deals, observers are sceptical.
"The regime is clearly not interested in negotiations or compromise and is the principle obstacle to peace," said Payton Knopf, the head of the South Sudan working group at the US Institute for Peace and former coordinator of the UN Panel of Experts on South Sudan.
Rights groups have blamed the government for systematic attacks on civilians in Equatoria, including killings, torture and rape.
As a result, many have sought shelter behind rebel lines, offering opposition fighters food in return for protection. But over the past couple of months, there have also been growing allegations of abuses at the hands of the SPLA-IO, gradually eroding popular support for the rebellion.
For the rebels, weakened by lack of ammunition and infighting, the loss of Lasu is just the latest in a series of military setbacks.
Civilians like Betty Moriba see little point in returning to South Sudan.
"I just want to be in one place, where I can raise my children," she said. "I just don't want to run anymore."