Congo's army and Rwandan-backed rebels are reinforcing military positions and blaming each other for flouting peace accords in an escalation that experts say risks reigniting the simmering conflict, which US President Donald Trump claims to have ended.
The M23 rebels seized two major cities in eastern Democratic Republic of Congo in January and February, posing the biggest threat to the government in Kinshasa in two decades. The offensive raised fears of a return to regional war as neighbouring armies took sides.
There has since been a series of US and Qatari-led peace talks, but those efforts have been undermined by mediators rushing to close deals and relying on past agreements ground out by African negotiators before building trust between the warring factions, the experts said.
The rebels want prisoners freed before talks can advance, as well as a power-sharing deal in the parts of Congo they now control. Congolese President Felix Tshisekedi's government, meanwhile, refuses to yield authority in territory it has lost or hand over any prisoners.
Reuters talked to four Congolese government officials, three rebel officials, six diplomats, two former officials and two Congo experts for this story.
Both sides are now dispatching hundreds of men to multiple frontline towns in Congo's eastern provinces bordering Rwanda and Burundi, where violence continues unabated while the talks rumble on, according to the Congolese government and rebel officials.
The UN and human rights groups have documented hundreds of summary killings, as well as torture and rape committed by both sides since preliminary peace agreements were signed, first in Washington and then in Doha.
In June, US mediators brokered a peace deal between Congo and Rwanda aimed at ending the support that Washington and UN experts say Kigali provides the rebels. A parallel Qatari-led peace effort was meant to seal an agreement between Kinshasa and the rebels, but it missed an August 18 deadline.
A Qatari spokesperson and the State Department did not respond to requests for comment on this story.
With a deadline to implement part of the US deal due in September, Kristof Titeca, a University of Antwerp professor who has studied Congo for decades, said there was no sign of peace.
"Broken promises, fragile implementation and deep mistrust are holding back any progress," he said. "All this creates what looks like a never-ending vicious circle."
Trump has said US companies eyeing a slice of Congo's mineral wealth would invest billions of dollars if the fighting ends.
That would require solving a conflict that has its roots in Rwanda's 1994 genocide, which triggered a series of wars in Congo that have killed, maimed and displaced millions of people, according to the UN.
After the genocide, in which about 1 million Tutsis and moderate Hutus were killed, the remnants of the defeated Hutu militia fled to Congo, forming a group known as the FDLR. Since then, the FDLR has preyed on civilians and taken part in Congo's various on-off wars, at times allied with the government in the capital Kinshasa.
The M23 rebels are the latest uprising that emerged to protect Congo's Tutsi. Rwanda denies backing the rebels but says it will do anything needed to defend itself from the FDLR.
Kinshasa accuses Kigali of using M23 as a proxy for pillaging valuable minerals from Congolese territory and says Rwanda's army has committed "massive and systematic crimes".
UN experts have documented the export via Rwanda of large quantities of looted minerals such as gold and coltan – which is used in mobile phones, computers and other technology. M23 now control the supply chain , from the mines to the border.
Jason Stearns, a former UN investigator with decades of Congo experience, said Rwanda only caved to enormous pressure from Washington to strike a deal knowing it had a loophole.
"That loophole was M23," said Stearns, now a professor at Simon Fraser University in Canada. "Rwanda can always say that it doesn't control the M23."
A spokesperson for Rwanda's government did not comment. Kigali has previously said U.N. reporting "misrepresents Rwanda's longstanding security concerns" about the FDLR threat.
An official in the presidency who declined to be identified said: "The rebellion's objective is to overthrow the government; it is therefore important to reinforce the frontline to counter M23 offensives."
Established in 2012, M23 briefly seized Goma - the capital of Congo's North Kivu province and home to 1 million people - before withdrawing under diplomatic and military pressure. A decade later, fighters in bases near Congo's mountainous border with Uganda and Rwanda took up arms again.
Thousands were killed in the January rebel advances. The United Nations says some 7.8 million people are now displaced.
M23 currently has at least 14,000 troops across North and South Kivu, including 9,000 newly trained recruits, according to two U.N. sources and three diplomats.
A flashpoint is emerging at a frontline town called Uvira on the shore of Lake Tanganyika in South Kivu.
M23, Rwandan forces and an allied local Tutsi-led militia have advanced and are facing off there with hundreds of fresh Congolese government troops, Burundian army allies and pro-government militia fighters known as Wazalendo, according to the seven Congolese government and rebel coalition sources.
"If they stay long in these positions, they will be impossible to dislodge," a senior Congolese army official said, in a reference to the inaccessible high ground the rebel alliance now controls.
In August, M23 accused Kinshasa and its allies of near-daily drone and artillery attacks on Tutsi known as Banyamulenge, seeking to isolate them in the highlands of South Kivu.
"Those that aren't dying by drones or gunfire are dying slowly of hunger," said Freddy Kaniki, one of the leaders of the alliance that includes M23.
An official with Congo's presidency denied attacking Tutsi communities and said the army was in a defensive position.
The Congolese army is itself still regrouping after the M23 offensive in early 2025 left it in disarray.
Another flashpoint is Walikale, home to a mine producing around 6% of the world's tin. There, the government has hired dozens of foreign military contractors to support troops, two diplomats and two residents told Reuters. Contractors with private security firm Agemira are also in Kisangani, a gateway to the east, UN experts said in July.
Erik Prince, a Trump supporter who offers security services worldwide, has signed a security deal with Congo's government, but has yet to deploy personnel, according to a person familiar with the operation. Prince declined to comment on the timing of the expected deployment.
Since the resurgence of M23 in 2022, African leaders have tried to end the fighting through diplomacy and sending troops.
In 2024, Angola brokered a deal between Congo and Rwanda that aimed to disarm the Hutu rebels in exchange for the withdrawal of Rwandan troops. The agreement was not implemented before fighting escalated.
US diplomacy, which re-committed Rwanda and Congo to the deal brokered by Angola, has yielded some modest gains.
In March, US pressure on Rwanda led to M23 withdrawing from Walikale, the tin mining town they briefly held.
"A few months ago, the idea that M23 and the Congolese would even speak was considered impossible," Troy Fitrell, until July, the top Africa diplomat at the State Department, told Reuters.
But only a handful of rebel and government negotiators remain in the Qatari capital, M23 and Congo's government said. M23 said in July that Congo must release some 700 prisoners for talks to advance. Kinshasa has not released any since.
Qatar has proposed establishing a new force made up of M23 and Congolese police to secure the area for five years, according to a draft agreement.
On August 30, Tshisekedi cast doubt on the need for outsiders to help broker peace, telling cheering party supporters that mediation was unnecessary.
"Allow us to resolve Congo's problems among ourselves," he said.
In response, M23 accused Kinshasa of violating the ceasefire and breaking promises.
An official with Congo's presidency later said the comments were in reference to African-led efforts and Kinshasa remained committed to the Qatar and US processes.
On September 3, US, Qatari, Congolese and Rwandan officials recognised there were delays and continued violence, but said all sides remained committed to the peace process.
