The experts cited former Rwandan officers and senior Congolese army officers, who estimated that, in total, well over 1,000 Rwandan troops went Congo to assist in the Kibumba operations.
The M23 and Rwandan military used night vision goggles, usually used by Rwandan special forces, during the nighttime advance on Kibumba, as well as heavy weaponry including 120mm mortars, which the experts said Makenga obtained from support networks in Rwanda and Uganda before he deserted from the Congolese army in May. The letter included a photo of 120mm mortars said to come from Makenga's private stock.
"The group learned through diplomatic sources in the region that the government of Rwanda had sought assistance to destroy 120mm mortars still within its arsenal in August 2012 in anticipation of eventual accusations of Rwandan weapons supplies to the rebels," the letter said.
When M23 progressed toward Goma on Nov. 19, Rwandan units operated alongside the rebels in combat at the airport and close to a post in Goma on the Rwandan border, the experts said.
On Nov. 20, they said, M23 defeated the Congolese army at the Goma airport and a mixture of rebel and Rwandan troops clandestinely entered into Goma from the Rwandan town of Giseny, just across the border.
They took control of the city, marching through downtown dressed in a combination of Rwandan and new M23 uniforms, the experts said.
The experts said that former Rwandan officers, Congolese government officials and Congolese officers estimated that roughly 500 soldiers from Rwanda's 73rd and 75th battalions based in Gisenyi supported the M23 during the seizure of Goma.