Peacekeepers deployed with the U.N. Mission for the Stabilization in the DRC uncovered the bodies of 21 civilians, including infants, women and children, who were beheaded or otherwise butchered in North Kivu province.
"These atrocities will not [go] unpunished and the perpetrators will know no respite as long as they have not been held accountable for their actions before the law," Kobler said in a statement Monday.
Kobler said it was unclear which armed group in eastern DRC committed the attacks but unconfirmed reports pointed to National Army for the Liberation of Uganda and the Allied Democratic Forces, two of the many armed groups fighting in North Kivu province.
A progress report on DRC published Monday by the European Union expressed optimism over a recent peace deal signed between the Congolese government and the rebel March 23 Movement. It expressed concern, however, over the activity of the many rebel groups left fighting in the country.
Kobler said the U.N. mission deployed attack helicopters and foot patrols to the province after discovering the bodies.
A special brigade within the peacekeeping mission is mandated to use force to help the Congolese military bring stability to the eastern provinces.
Notable deaths of 2014 [PHOTOS]