A soldier walks past the armoured personnel carrier just as it sparks and smokes, sending a surface-to-air missile hurtling toward the United Nations drone filming it from above.

The location is 12 miles inside the Democratic Republic of Congo’s North Kivu province. The soldiers manning the Chinese-made Type 92 Yitian vehicle are Rwandan, according to Western military analysts who viewed the drone footage seen by Bloomberg. They are deep in foreign territory where their government loudly proclaims they’re not active, fighting alongside brutal rebel forces it says it doesn’t support.

Forty miles away, Niyonzima Nyandwi recounts how he was recruited by the M23, a rebel militia that UN investigators accuse of war crimes, after the group captured his village late last year.

Foreign powers including the US, the European Union and Congo, as well as the UN, accuse Rwanda of backing M23, a group of about 4 000 combatants that says it’s fighting to protect ethnic Congolese Tutsis.

“The men who trained us had Rwandan flags on their military uniforms,” Nyandwi said, sitting in his tent at the Shabindu camp, one of dozens in the region that host hundreds of thousands of the 6-million people displaced in one of the world’s most brutal wars.

Conflict has simmered in eastern Congo since the mid-1990s in the aftermath of the Rwandan genocide, exploding into two wars that left millions of people dead. The fighting, which intensified in late 2021 and involves dozens of armed groups, long-running ethnic tensions and at least five national armies, has now reached a peak not seen in at least a decade. Among the groups that operate in eastern Congo are Hutu militias that perpetrated the 1994 Rwandan genocide — in which 800 000 mostly ethnic Tutsis died — before fleeing across the border and birthing the armed group known as the Democratic Forces for the Liberation of Rwanda, or FDLR. That group is now allied with Congo’s army, known as the FARDC, against the M23.

Since late 2022, the M23 has doubled the amount of territory under its control, according to UN investigators, and in February surrounded the key hub of Goma, choking off supplies from some of the world’s richest deposits of tin ore and coltan, minerals used in semiconductors and mobile phones. While Rwanda doesn’t acknowledge it supports M23, the US and others have all called on Kigali to cease backing the rebel group.

“The United States condemns Rwanda’s support for the M23 armed group and calls on Rwanda to immediately withdraw all Rwanda Defence Force personnel from the DRC and remove its surface-to-air missile systems, which threaten the lives of civilians, UN and other regional peacekeepers, humanitarian actors, and commercial flights in eastern DRC,” the US State Department said in a statement in February.“What is missing from the coverage of the situation in the DRC is any context explaining why Rwanda would be concerned with the situation there,” Rwandan government spokesperson Yolande Makolo said in an emailed response to questions.

“We have no intention of responding to baseless allegations promoted by those fighting alongside the FARDC, ‘officials’ and supposed ‘defectors,’” she said. “They are the very definition of unreliable sources. The FARDC are aligned to the FDLR, a genocidal group committed to the violent overthrow of the Rwandan government and the eradication of all Tutsi.”

Rwanda has deployed about 3 000 troops to eastern Congo, according to three western officials in the region, and trains M23 rebels at a remote camp near the countries’ border, five ex-fighters who trained there said. It’s unleashed an unprecedented flood of arms to the rebels – including fixed-wing drones, Israeli-made grenade launchers, drone jammers and Russian SPG-9 anti-tank grenade launchers, according to UN investigators and data shared with Bloomberg by a military contractor hired by the Congolese army to fight M23.

“The M23 at present is more powerful than it has ever been, so Rwanda is clearly flexing its muscles to its maximum degree,” said Richard Moncrieff, an analyst at the International Crisis Group. Neither Rwanda nor the Congolese government, which employs foreign mercenaries and backs both militias and armed vigilante groups that are accused of committing atrocities, show any signs of backing down.

That raises the prospect of the sort of conflict the region hasn’t seen since Rwanda twice invaded Congo in the late 1990s to overthrow successive governments and fight the ethnic Hutu militias that perpetrated the genocide and fled across the border.

“We've probably never really been as close to the potential for real war between Rwanda and the DRC as we are now,” said Stephanie Wolters, an analyst at the South African Institute of International Affairs. “All of the elements are at their peak, which is incredibly bad for eastern Congo and for the region as a whole.”

The conflict is the prime example of Rwandan President Paul Kagame's increasing defiance of Western countries that have poured billions of dollars in aid into Rwanda since the genocide and held Rwanda up as a model of development – and show little sign of forcing him to stop. In a sign of how Kagame generally manages to have it both ways, the EU earlier this year agreed to source critical minerals from Rwanda, even as it simultaneously joins the international chorus calling for Kigali to stop fueling the fighting in Congo.

“Kagame has made a calculation that he is too useful and too popular with his international allies – particularly Western, but not only Western – for them to seriously punish him or isolate him over what he’s doing in Congo,” Moncrieff said. “So far, that calculation has proven correct.”

The Congolese government didn’t respond to a request for comment. Rwanda’s support is crucial to the success of the M23, but the rebels have their own motivation for land, minerals and local taxes, which they collect on roads and in villages to the tune of hundreds of thousands of dollars a month, according to an April report by the Belgium-based International Peace Information Service. Even then, it has only ever dramatically expanded its territory when Rwanda turns on the funding taps.That was the case the last time after the M23 took Goma, in 2012: the US imposed sanctions, donors suspended hundreds of millions of dollars in international aid and African nations deployed an intervention force. That forced Rwanda to soften its support and the rebel group went quiet.

Since then, Kagame has bolstered his reputation as a ruthlessly efficient autocrat. He’s transformed the country into perhaps the West’s most important African ally – its widely respected army is a top UN peacekeeping contributor and protects both foreign energy projects and African presidents – even as he’s accused by advocacy groups including Human Rights Watch of suppressing dissent and curtailing human rights.

In Goma, a city of 2-million people, signs of the M23’s dominance are everywhere: armed groups and Congolese soldiers have taken up positions about 12 miles outside the city and civilian and military casualties from the frontlines can often be seen being rushed to local hospitals.

While part of Rwanda’s interest in eastern Congo is keeping the FDLR at bay, another major factor is the abundant mineral wealth – which helps fund the M23 and dozens of other rebel groups active in eastern Congo.

The M23’s recent success in expanding its territory has brought about major shifts in Congo’s mineral industry.

North Kivu went from exporting 620 tons of coltan worth $27-million in 2023, data from the provincial mining department shows, to recording almost no exports in the first quarter of 2024 as the M23 cut off supply lines. Artisanal tin-ore shipments for the province in 2023 totalled 1 026 tons worth $9.7-million, but have also fallen to almost zero.

Congo’s ability to trace anything it produces artisanally in North Kivu has essentially collapsed – almost all of its artisanal production is now smuggled out, according to local mining officials.

“Deflecting attention onto Rwanda with false accusations that Rwanda is causing conflict to enrich itself with Congo’s natural resources is a scapegoating strategy by the Kinshasa government,” Makolo said. “They’re trying to cover up the true causes of the instability in the DRC – which are essentially security and governance failures and the persecution of a part of the Congolese population.”

Kagame has long denied that Rwanda benefits from what Congo claims is the $1-billion a year it loses from the smuggling of gold and other minerals through Rwanda.

“The Congolese are saying we’re stealing their coltan, we’re stealing their gold,” he said in remarks in Kigali in 2022. “But most of it goes through here – it does not stay here. It goes to Dubai, it goes to Brussels, it goes to Tel Aviv… It goes everywhere.”

Raphaël Mboko Kaponyola, who runs the North Kivu provincial mining division office in Goma, said mineral smuggling into Rwanda has gotten worse since the M23 last year took control of the region’s main export routes from the Rubaya mine, the country’s biggest coltan producer. He also slammed the EU’s recent deal with Rwanda to “nurture sustainable and resilient value chains for critical raw materials.”

“We have been completely cut off. And meanwhile we see the European Union, instead of coming here, they sign deals over there,” he said. “They are treating us like idiots.”Congo signed a similar deal on critical-mineral supplies with the EU in October.“The MoUs signed with Rwanda and DRC are fully in line with the EU Great Lakes Strategy adopted on 20 February 2023 to formalise regional trade of minerals and sustainable development,” a European Commission spokesperson said in an emailed response to a request for comment. “The EU is not taking sides in the conflict, and has always maintained a balanced approach.”

Earlier this month, at the Mubambiro military base near Goma, the Congolese army’s 3408th regiment was conducting shooting drills under the instruction of mercenaries from the Bulgaria-registered private military contractor Agemira.

“You have all this equipment coming in that we have never seen in the DRC before and also does not exist inside the Congolese army’s arsenal,” said Hugo, a French Agemira mercenary who asked to be identified only by his first name for security reasons. Beyond grenade launchers and 120 millimeter mortar rounds, he said, the Rwandan army is now using jammers to interfere with Congolese surveillance drones.

Agemira estimates that Congolese forces it advises have killed 250 uniformed Rwandan soldiers in Congo, Hugo said. The mercenary group provided Bloomberg with dozens of photographs taken using the army’s drones that it said showed Rwandan soldiers patrolling in formation in Congo. Agemira identified the soldiers in the pictures by the colour of their uniforms, helmets and bulletproof vests.

Bloomberg couldn’t independently verify the soldiers’ identity, but in the displacement camps that dot the hills around Goma, a dozen men and women who had fled the conflict described uniformed soldiers with Rwandan flags on their sleeves holding meetings with, recruiting for and training M23 fighters.

Crime and sexual violence are rampant in the camps, where Doctors Without Borders is recording 1 500 cases of rape a month and the conflict has escalated so much that clashes between armed groups are breaking out in the camps themselves, said Marie Brun, the group’s emergency coordinator.

“There have been grenades exploding in the camp and more and more cases of sexual abuse,” she said.

Clémentine Baséme, 45, said she was the victim of one such assault, when she was gathering firewood near her village last January. She fled to Kanyaruchinya camp outside Goma and lives there with her nine children. Now, as violence explodes all around her, she fears she may have to move again.“When we fled our village and came to the refugee camp we escaped violence,” she said. “If the M23 take Goma, we will have to flee again. Bullets will fly overhead and we will have to flee.”