DR Congo–Rwanda border

A missing mountain

In 1885 the Congo Free State of King Leopold II declared its eastern limit to be the 30th meridian, then a straight line to Lake Tanganyika. In 1890 Britain and Germany split their spheres along 1° S, bending only to put “Mount Mufumbiro” in British hands. Mufumbiro later turned out to be a whole region of volcanoes lying south of 1° S and west of the 30th meridian, in land the Congo claimed.^[1]

Boundaries between Lake Kivu and Lake Albert had been drawn with little knowledge of the ground. A British, German and Belgian conference in Brussels in 1910 sorted it out, making the summit of Mount Sabinyo the meeting point of the three colonies, and a Belgian–German convention of 11 August 1910 described the line between the Belgian Congo and German East Africa, which included Rwanda.^[1]

Islands and volcanoes

The convention ran the boundary along the main channel of the Ruzizi to Lake Kivu, then across the lake on a line that gave Idjwi, the largest island, and three others to Belgium, and four small islands to Germany. North of the lake it followed the meridian halfway between the Belgian post at Goma and the German compound at Gisenyi, bending where it could to keep villages in German territory, then ran through the volcanoes Karisimbi and Visoke to Sabinyo.^[1]

The southern part lies in the western branch of the Great Rift Valley. Lake Kivu, about 1,100 square miles and 1,600 feet deep, drains south through the Ruzizi to Lake Tanganyika and is served by the ports of Goma and Bukavu in Congo and Gisenyi in Rwanda. In 1965 there was no official dispute over the line, though Congolese had made unofficial claims to three of the small Rwandan islands.^[1]

“The summit of Sabinio marks the point where the German, Belgian, and British territories join.”^[1]

War in the east

Rwanda says its security concerns are driven by the Democratic Forces for the Liberation of Rwanda (FDLR), a militia made up largely of Hutus who fled to Congo after taking part in the 1994 genocide, and accuses Congo’s government of supporting it. More than 100 armed groups operate in eastern Congo, and the conflict has displaced more than seven million people.^[2]

In 2025 M23 rebels, whom the UN describes as Rwanda-backed, occupied the region’s largest cities, taking the Lake Kivu port of Bukavu in February.^[3][2][1] Congo’s President Félix Tshisekedi and Rwanda’s President Paul Kagame signed the Washington Accords for Peace and Prosperity in December 2025, but fighting went on, and M23 took Uvira days later.^[3][2]

On 19 December 2025 the UN Security Council unanimously condemned Rwanda for backing the offensive and urged it to withdraw its forces. Rwanda has consistently denied backing M23, despite assessments by UN experts.^[2]