AFC/M23 captured Rubumba on Saturday in a fresh push into the mid-level plateaus of Uvira, raising fears of an imminent advance toward the Ruzizi plain.
Local reports say the group also seized Kitoga, Bibangwa, Rubuga, and Masango in the same offensive.
The move brings the rebels closer to Uvira, a strategic city on the shores of Lake Tanganyika.
The fighters seek to replicate the encirclement strategy used in the fall of Goma; gradually surrounding the city, cutting off supply lines, and striking at the opportune moment.
Rather than pushing directly along the RN5 highway from Bukavu through the heavily defended Ruzizi plain, M23 appears to be securing the high and mid-level plateaus, where the allied Twirwaneho militia already holds strong positions.
The earlier fall Kanyola and Nindja, two weeks ago, is seen as part of a broader plan to open a corridor for rebel fighters to move toward Uvira.
With Rubumba now under their control, Kageregere and Kashatu in the Runingu grouping; just 30 minutes from central Uvira; are viewed as likely next targets.
M23’s methodical gains across the plateaus in recent weeks indicate that Uvira may soon fall in their hands.
Uvira is stronghold of Wazalendo government militia and Burundian forces. They have notoriously wreaked havoc since February, looting and killing mercilessly.
For the communities of Uvira, the capture would be a long waited relief.