What we know about M23's new advance in DR Congo

A woman balances a sack of flour on her head as she crosses a road in Uvira on December 9, 2025.[AFP]

A Rwanda-backed militia late Wednesday seized control of most of the city of Uvira, the last government stronghold in the mineral-rich eastern Democratic Republic of Congo's South Kivu province.

Advancing from the north near the Burundian border, the M23's assault came only days after the leaders of the DRC and Rwanda signed a US-brokered peace deal in Washington.

Here's what we know about the latest M23 offensive:

Why Uvira?

Nearly 18,000 Burundian soldiers are deployed alongside the Congolese army in South Kivu province, notably in the Ruzizi plain, which borders Burundi.

"The push to have Burundi disengage I think, is an important objective" of the M23 offensive, according to Bram Verelst, a researcher at the Institute for Security Studies (ISS).

Controlling Uvira and the border plain would allow the M23 to block support arriving by land from Burundi.

The group could then push on towards Tanganyika province, and beyond that to the copper- and cobalt-rich Haut-Katanga province.

For months, the M23 and the Rwandan army chipped away at the South Kivu highlands at the expense of the Congolese and Burundian forces defending Uvira.

The latest offensive -- launched on December 1 -- has further shaken hopes that an agreement brokered by US President Donald Trump will succeed in halting the conflict.

According to experts, the latest violence could be a way for the anti-government group and Kigali to increase pressure on Kinshasa.

Consequences for Kinshasa?

Congolese President Felix Tshisekedi made the fight against the M23, or what he calls "Rwandan aggression", a priority of his second term.

But earlier this year, the army suffered a major defeat when the M23 seized Goma and Bukavu, two provincial capitals in the mineral-rich east, which has been plagued by conflict for around three decades.

Deprived of military support from its Burundian neighbour, the Congolese army -- poorly equipped and riven by internal divisions -- does not appear capable of stemming the M23's advance.

"This is yet another heavy blow" for Kinshasa, said Pierre Boisselet from the Congolese Ebuteli research institute.

The DRC faces mounting pressure to make new concessions in the ongoing peace process, he added.

"But these will be all the harder to accept and to sell politically after this setback."

 Risk to regional stability? 

In a region marked by longstanding communal divisions, relations between Rwanda and Burundi were already thorny.

As heavy fighting raged near their shared border in the DRC, the two neighbours traded accusations of dropping bombs on each other’s territory, stoking fears of a wider conflict.

Burundian Foreign Minister Edouard Bizimana on Wednesday said his country was "ready to use all means to protect its borders".

"However, it's not certain we'll see a direct confrontation in the very short term," said Boisselet.

But "the loss of Uvira will pose serious medium- and long-term" economic and security problems for Burundi, he added.

With Burundi heavily reliant upon access to the Congolese market, Verelst said the border closure could have "significant economic effects".

US response?

The rapid advance by the M23 alongside the signing of a peace agreement -- which Trump called a "miracle" deal -- took many by surprise.

The M23 ran "the risk of humiliating Donald Trump, but apparently, that didn't deter them", Boisselet said.

"Signing an agreement and not implementing it is a humiliation for everyone, and first and foremost for President Trump," Bizimana, Burundi's foreign minister, told AFP on Wednesday.

"It's truly a slap in the face to the United States, a middle finger," he said, calling for sanctions against Rwanda.

On Tuesday, the United States and European powers urged the M23 to "immediately halt" its offensive and for Rwanda to pull its troops out of the eastern DRC.

But a "strong reaction" from Washington remains to be seen, according to Verelst.

"The United States must now use the peace agreement that they themselves oversaw to secure Rwanda’s withdrawal," he said.