EASTERN CONGO — The Congo River Alliance accused the United States of falling short as a mediator in efforts to end the conflict in eastern Congo, according to a letter sent to U.S. Secretary of State Marco Rubio. The letter was written by Corneille Nangaa, a Congolese rebel leader, and signed by the alliance, which includes the Rwanda-backed M23 rebel group.

The letter criticized the U.S. for sanctioning actors critical of the authorities in power in Kinshasa. The letter said, "The absence of clearly identifiable corrective measures raises questions about the facilitation's ability to maintain impartiality and neutrality over time."

Last week, the U.S. imposed sanctions on former President Joseph Kabila over his alleged role in funding and supporting the rebels. Earlier this year, the U.S. sanctioned Rwanda's military and four of its senior officials for supporting M23. Congo, the U.S., and United Nations experts accuse Rwanda of backing the group.

Congo and Rwanda agreed in 2025 to a U.S.-mediated peace deal aimed at ending the conflict in eastern Congo. The agreement defined terms of economic partnership among Congo, Rwanda, and the U.S. and aimed to unlock deals on rare earth minerals. At the time of the agreement, U.S. President Donald Trump praised Presidents Felix Tshisekedi of Congo and Paul Kagame of Rwanda.

Fighting has continued in the region, with both rebel and government forces accusing each other of violating the peace terms. M23 fighters seized Goma and other key cities early last year as they expanded their presence in eastern Congo. According to the United Nations, M23 grew from hundreds of members in 2021 to around 6,500 fighters.

Eastern Congo has experienced decades of unrest as government forces fight more than 100 armed groups, the most potent being M23, often over access to mineral resources. The Congo River Alliance letter was addressed directly to Rubio, signaling that the alliance is appealing to U.S. leadership over the direction of the mediation process.