South Sudan's First Vice President, Riek Machar, longtime rival to President Salva Kiir, was arrested on Wednesday, sparking fears of renewed conflict.

A convoy of armed vehicles stormed his Juba residence, escalating tensions as the fragile power-sharing deal collapsed, risking a return to the civil war that claimed 400,000 lives.

Commenting on the incident, his party, the Sudan People's Liberation Movement In Opposition (SPLM/IO), maintained that the arrest has effectively collapsed the 2018 peace deal that ended the country's five-year civil war.

Machar was detained alongside his wife Angelina Teny, who is the country's interior minister, the party added.

"The arrest and detention of H.E Dr Riek Machar effectively brings the [peace] agreement to a collapse," said SPLM/IO deputy leader Oyet Nathaniel Pierino.

A statement on Facebook, shared by Reath Muoch Tang, a senior SPLM-IO official, said, "We strongly condemn the unconstitutional actions taken today by the Minister of Defense and the Chief of National Security, who, alongside more than 20 heavily armed vehicles, forcefully entered the residence of the First Vice President."

"His bodyguards were disarmed, and an arrest warrant was delivered to him under unclear charges. Attempts are currently being made to relocate him," it added.

The government has yet to comment on Machar's reported house arrest.

On Thursday, the United Nations Mission in South Sudan (UNMISS) said the reported arrest left the country on a precipice.

In a statement, UNMISS head Nicholas Haysom said, "Tonight, the country's leaders stand on the brink of relapsing into widespread conflict." Breaches of the 2018 peace deal "will not only devastate South Sudan but also affect the entire region," he added.

Rival forces clash amid political tensions, arrests

Since February, over 20 of Machar’s political and military allies have been arrested, many held incommunicado.

Clashes between rival forces have erupted, particularly in Nasir County, Upper Nile State. Machar’s party claims government forces have attacked a military base and two training centers near Juba since Monday.

A spokesman for Machar’s military wing, the SPLA-IO, condemned the attacks as “terrorism” in a Facebook post, urging international intervention.

The targeted training centers were meant to integrate opposition forces into a unified army under the 2018 peace deal. The Kiir-aligned SSPDF has not confirmed the incidents but accused Machar’s forces of aggressive maneuvers on Monday, as the escalating clashes and political tensions have left many in Juba uneasy.

"I am so worried about the situation. I feel like we are going back to war while we still need peace," Lilian Sukeji told AFP, adding, "Our leaders need to embrace dialogue rather than guns."

Before Machar's arrest, President Kiir reiterated his dedication to peace after talks with church leaders. However, this promise follows rising violence, particularly in Nasir County, where Kiir’s forces clashed with the White Army, a militia connected to Machar.