Civilians in SPLA-IO-held counties in South Sudan should evacuate immediately amid the "imminent" launch of an operation against rival forces, the army has ordered

South Sudan's army has ordered civilians and personnel from the UN mission (UNMISS) and humanitarian organizations to evacuate three counties in Jonglei, the country's largest state, as it prepares for an operation targeting opposition forces.

Jonglei has experienced the fiercest fighting in Africa's youngest country in recent months, with clashes between the South Sudan People's Defense Forces (SSPDF) and the Sudan People's Liberation Army-in-Opposition (SPLA-IO) described by the UN as the most intense since 2017.

SPLA-IO forces, aligned to South Sudan's suspended Vice President Riek Machar, captured the town of Pajut in northern Jonglei in mid-January, bringing the state capital Bor into closer range of their offensive.

In a statement on Sunday, SSPDF spokesperson Maj. Gen. Lul Ruai Koang announced the "imminent" launch of 'Operation Enduring Peace' and directed all civilians in SPLA-IO-held areas of Uror, Nyirol, and Akobo to immediately evacuate to nearby government-controlled areas for their safety.

"All NGOs and UNMISS personnel operating and working in Nyirol, Uror, and Akobo counties are given 48 hours to leave," he stated, urging "armed civilians not interested in fighting with government forces to immediately hand over their rifles" to the SSPDF.

South Sudan gained independence from Sudan in 2011 but it has remained volatile since the end of a five-year civil war that erupted in 2013 over a feud between President Salva Kiir Mayardit and his current first vice president, Machar. The conflict displaced millions and left an estimated 400,000 dead.

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Kiir and Machar govern South Sudan under a 2018 power-sharing agreement, but tensions flared last March after the vice president was arrested on charges of murder, treason, and crimes against humanity.

The UN mission in South Sudan warned of a threat of escalating violence in Jonglei on Sunday after Deputy Army Chief Gen. Johnson Olony told troops to "spare no one - the elderly, children, birds - or leave no house standing" when deployed to opposition-held areas.

The mission reported that more than 180,000 people have fled their homes due to the hostilities, urging the warring factions to return "to consensus-based decision-making" and adhere to power-sharing arrangements.