According to a 131-page report by experts for the UN Security Council, Rwanda has launched military interventions inside Congolese territory since at least November 2021.
Rwanda also "provided troop reinforcements" for specific M23 operations, the report said, "in particular when these aimed at seizing strategic towns and areas."
The M23 -- for "March 23 Movement" -- is a primarily Congolese Tutsi group.
After lying mostly dormant for years, the rebel group resumed fighting late last year.
On May 25, the report said, a large DRC army base in Rumangabo in eastern North Kivu province came under heavy mortar and small-arms fire.
M23 fighters and Rwandan troops "jointly attacked" the site after Rwandan troops had crossed into the DRC the day before, it alleged.
An estimated 1,000 Rwandan troops also cut the main highway leading to the provincial capital Goma, an important commercial hub on the Rwandan border, and attacked Congolese positions, it said.
On the eve of the attack on Bunagana, and on the day itself, Rwandan soldiers were in the vicinity, the report said, citing drone images from the UN peacekeeping mission in the DRC, eyewitnesses, amateur videos and photos.
"On repeated occasions, aerial imagery showed large columns of up to 500 armed men in the vicinity of the DRC, Rwandan and Ugandan borders, moving in a very organized manner," the report said.
The columns of soldiers wore "standardized military attire" that bore close resemblance to Rwandan army uniforms, the report added.
Some 300 Rwandan troops also conducted operations against rebel groups in eastern DRC, such as the Democratic Forces for the Liberation of Rwanda (FDLR).
The FDLR is a Rwandan Hutu rebel group based in the DRC, which the Rwandan government views as a threat. Kigali has regularly accused Congo of supporting the militia.
The investigation also found that DRC forces had been providing support for armed groups in the deeply troubled east.
On May 26, after being dislodged from positions near the Goma highway, the Congolese army launched a counterattack alongside militia fighters, for example.
A coalition of armed groups had formed in May, with the knowledge of Congolese officers, the report said.
Leaders of several militias confirmed to the experts that the Congolese army had provided them with weapons and munitions "on several occasions," it added.
The DRC and Rwanda have had strained relations since the mass influx of Rwandan Hutus accused of slaughtering Tutsis during the 1994 Rwanda genocide.
The DRC and Rwanda have had strained relations since the mass influx of Rwandan Hutus accused of slaughtering Tutsis during the 1994 Rwanda genocide.
Relations began to thaw after DRC President Felix Tshisekedi took office in 2019 but the M23's resurgence reignited tensions.
