Democratic Republic of Congo President Felix Tshisekedi has vowed “a vigorous and coordinated response” against a rebel alliance that has besieged swaths of the nation’s mineral-rich east and forced hundreds of local troops and foreign mercenaries to surrender.

Angolan President Joao Lourenco, who’s been mediating peace talks between Rwanda and Democratic Republic of Congo, called for the withdrawal of Rwandan-backed M23 rebels from the city of Goma and for Rwandan troops to leave Congolese territory.

Rwandan President Paul Kagame has told CNN he doesn’t know if his country’s troops are in the east of the Democratic Republic of Congo (DRC), where fighting between the M23 armed group and Congolese soldiers has killed more than 700 people and injured thousands in recent days.

The Congolese government, alongside U.N. officials and Western powers, including the United States, has accused neighbouring Rwanda of exacerbating the conflict by deploying thousands of troops and heavy weaponry in support of M23.