Rebels in the Democratic Republic of Congo have surrounded the eastern city of Goma, in one of the sharpest escalations in years of a conflict that has pitted the Central African country against its neighbor Rwanda.

On Thursday, fighting raged between rebels from the Rwanda-backed M23 group and Congolese forces in the town of Saké, the last major army position before Goma, a provincial capital with more than 2 million people. On Tuesday, M23 captured Minova, a key town along one of Goma’s main supply routes.

Goma’s fall would be a major milestone for M23. The group captured the city and held it for two weeks in 2012, but withdrew after Rwanda came under intense international pressure to stop backing the militia. The United States and United Nations say Rwanda funds and directs the M23, charges that Rwanda has denied.

In late 2013, the Congolese Army and United Nations forces quickly defeated the rebel group, which lay dormant afterward for almost a decade.

M23 has since surged back, starting in late 2021, dealing the Congolese Army a series of defeats. At the same time, peace talks spearheaded by Angola, Congo’s southwestern neighbor, have stalled, and the fate of U.N. peacekeepers stationed in eastern Congo was until recently up in the air, with their mandate renewed in December for another year.