South Africa's President Cyril Ramaphosa has ordered the deployment of 2,900 soldiers to aid in the fight against armed rebel groups in the eastern Democratic Republic of Congo.
The troops will be posted as part of the southern African mission in DR Congo (SAMIDRC), which was approved by the regional bloc in May last year.
Malawi and Tanzania will also contribute troops to the mission.
The mission is replacing the East African regional force, which left DR Congo last December after the government deemed it ineffective.
The deployment will cost South Africa 2bn Rand ($105m; £83m) and is set to last until December this year, a statement from the presidency said.
The announcement comes amid a resurgence of fighting that has seen tens of thousands displaced, added to the nearly seven million who have been forced from their homes in DR Congo because of multiple conflicts.