Deployment of troops comes after six people killed in days of protests in KwaZulu-Natal and Gauteng.
The South African military said it was deploying soldiers in two provinces, including its economic hub of Johannesburg, to help police cope with looting and arson attacks on businesses.
The move comes as the country’s top court began hearing a challenge on Monday by former president Jacob Zuma against a 15-month prison term.
Police said six people have been killed and more than 200 arrested in related protests and looting since last week.
“The South African National Defence Force has commenced with pre-deployment processes and procedures in line with a request for assistance received … to assist law enforcement agencies deployed in Gauteng and KwaZulu-Natal provinces respectively to quell the unrest that has gripped both Provinces in the last few days,” South African military said in a statement on Monday.
Zuma, 79, was sentenced for defying a constitutional court order to give evidence at an inquiry investigating high-level corruption during his nine years in office until 2018.
The decision to jail him resulted from legal proceedings seen as a test of post-apartheid South Africa’s ability to enforce the rule of law, including against powerful politicians.
In the virtual hearing, Zuma’s counsel asked the court to rescind his jail term, citing a rule that judgements can be reconsidered if made in the absence of the affected person or containing a patent error.
Al Jazeera’s Fahmida Miller, reporting from Johannesburg, said legal experts believe chances of the court rescinding its previous ruling are slim.
“The president’s lawyers are saying he did not choose to not appear before the constitutional court. They are saying it was his ill health which dictated that. They are hoping the court rescinds its previous judgement,” Miller said.
Violence and looting
Sporadic violence and looting continued on Monday after a weekend of unrest by pro-Zuma protesters, mainly concentrated in his home province of KwaZulu-Natal (KZN).
Some disturbances spilled into the country’s largest city, Johannesburg.
Shortly before the military’s announcement, troops were seen on the streets of its capital, Pietermaritzburg, and smoke billowed from the roof of a large shopping mall.
A retail shop in Durban was looted on Monday morning while in Eshowe, a town near Zuma’s Nkandla home, police fired rubber bullets to disperse crowds after a supermarket was ransacked.
In Johannesburg, in Gauteng province, an AFP news agency photographer saw a corpse at one site. The cause of the death was not immediately known. Sections of a major highway were closed.
Some of the protests appear to have been triggered by Zuma’s detention, but they are also associated with grinding unemployment and hardship inflicted by a toughening of anti-COVID measures.