Senegal President Macky Sall, who chairs the Africa Union, has called for dialogue between the Democratic Republic of Congo and Rwanda as tensions escalate between the two countries over a resurgence of the M23 rebel group. The Congo had on 28 May, summoned Rwanda’s ambassador and suspended RwandAir flights to Congo in response to what it says is Kigali’s support for M23 rebels carrying out a military offensive in its eastern borderlands.

Kinshasa has accused Rwanda of the latest offensive by the rebels, citing the rebels’ heavy firepower as evidence of outside support. Rwanda has denied this, calling the fighting an intra-Congolese conflict. Rwanda’s army also requested the release of two Rwandan soldiers it said were “kidnapped” along its border with Congo.

“I am seriously concerned by the rising tension between Rwanda and the Democratic Republic of Congo,” Sall said on Twitter. “I call for calm and dialogue between the two countries, and for the peaceful resolution of the crisis with the support of regional mechanisms and the African Union,” said Sall, who holds the rotating chairmanship of the African Union.

This comes amid heavy fighting raging in the eastern Democratic Republic of Congo on Thursday between the army and M23 rebels, who are waging their most sustained offensive since a 2012-2013 insurrection that briefly overran the major city of Goma. The army recaptured its base in Rumangabo from the M23 but the rebels still appeared to control much of the surrounding area, said Emmanuel de Merode, director of the Virunga National Park, who is based in the town.

There was also heavy fighting overnight near the town of Kibumba, about 20 km (12 miles) northeast of Goma near the border with Rwanda, de Merode added. M23 spokesman Willy Ngoma told Reuters that the rebels had routed the army and allied militias, which he said had started hostilities. Ngoma said the M23 was now satisfied, but when asked if the group might move on Goma, he added: “The day that will be necessary for our defence, we will not hesitate.” The M23 insurgency stems from the long fallout of the 1994 genocide in Rwanda.

The latest round of clashes threatens peace in a region now infested with armed groups and other allied non-state actors such as the Islamic State-backed Allied Democratic Forces who operate across borders. Rwanda’s denial is being taken with a pinch of salt as evidenced by the hundreds who have marched in anti-Rwanda protests in the Congo, calling on Mr Tshisekedi’s government to expel the Rwandan ambassador.

In many respects, the M23 crisis, which is a spillover of the Rwandan genocide, is the relic of a frozen conflict and must be looked at from this lens. The group’s leadership is from the Tutsi ethnic group and has justified its attacks by saying it is battling the Democratic Forces for the Liberation of Rwanda (FDLR), a militia founded by ethnic Hutus who fled Rwanda after participating in the genocide.

In 2012, the M23 captured Goma, a city of more than a million people, before being chased out by Congolese and U.N. forces into Rwanda and Uganda the following year. Late last Wednesday, the Congo’s government renewed accusations that Rwanda, led by Tutsi Paul Kagame, was backing the M23. Rwanda said it was not involved in what it described as an intra-Congolese conflict and in turn, accused the Congolese army and FDLR fighters of shelling Rwandan territory on 19 March and 23 May.

Rwanda’s foreign adventures in the region, in pursuit of what it describes as rebels, have done more to destabilise the DRC as it has demonstrably invaded and pillaged that country’s resources. There are suspicions that this is an active policy of the government in Kigali.

It is equally remarkable to note that the strongest international statement on the violence is coming from the chairperson of the African Union. The silence of the East African Community, which the DRC recently joined, is yet the biggest indicator that member countries are reluctant to engage in order to avoid a possible conflagration of the crisis. That is the wrong approach and a few wrong moves could easily swallow much of the region in armed conflict, risking a return to the 1990s and 2000s; a period so terrible it was often referred to as the ‘African World War.’