Ugandan special forces have been deployed to South Sudan’s capital Juba, the Ugandan army chief said Tuesday, after rising tensions threatened a fragile peace agreement between President Salva Kiir and Vice President Riek Machar.

Impoverished South Sudan has long been plagued by political instability and insecurity, but concerns have risen sharply in the past week after clashes between forces allied to the country’s leaders in the northeast.

“As of 2 days ago, our Special Forces units entered Juba to secure it,” Ugandan army chief Muhoozi Kainerugaba said on X.

“We shall protect the entire territory of South Sudan like it was our own,” the son of Ugandan leader Yoweri Museveni and infamous for his incendiary X posts, added.

Ugandan army spokesman Felix Kulayigye confirmed that troops had been deployed in the capital “to protect the government”.

“We had instructions to deploy and we deployed the troops there,” he told French news agency AFP.

Uganda sent troops to South Sudan in 2013 at the onset of a five-year civil war to support now President Salva Kiir, before officially withdrawing at the end of 2015.

A fragile power-sharing agreement between Kiir and First Vice President Riek Machar ended that conflict in 2018, but the deal has been threatened by the recent clashes in Upper Nile State.

Tensions flared last Friday after a UN helicopter was attacked during a failed rescue mission.

The UN Mission in South Sudan (UNMISS) said its team was attempting to extract members of the South Sudanese army from the area when their helicopter came under fire.

A South Sudanese army general and other officers were killed, UNMISS said in a statement, saying the incident may constitute a war crime.

Kiir urged citizens to remain calm, stating: “I have said it time and again that our country will not go back to war. Let no one take law into their hands.”

“The government which I lead will handle this crisis. We will remain steadfast in the path of peace,” he added.

Kiir’s allies have accused Machar’s forces of fomenting unrest in the region, in league with the so-called White Army, a loose band of armed youths from the same ethnic Nuer community as the vice-president.

Late Friday local media reported a statement from Machar’s office which condemned the helicopter attack as “barbaric”.

Efforts to “restore peace in the region remain a top priority,” the statement added, with Machar “continuing to engage all stakeholders to prevent further violence.”

The rising unrest has sparked international concern, with the United Nations Commission on Human Rights in South Sudan warning the country was seeing an “alarming regression” that threatened to undo years of progress.

The International Crisis Group think tank has warned that “South Sudan is slipping rapidly toward full-blown war”.

Its Horn of Africa director Alan Boswell urged the UN to prepare peacekeepers to save civilian lives, adding: “We fear large scale ethnic massacres if the situation is not soon contained.”