The FDLR (Forces démocratiques pour la libération du Rwanda) has been one of the most abusive armed groups in eastern Congo over the past two decades. The FDLR was formed by Rwandan Hutus linked to the 1994 genocide and includes former members of President Juvénal Habyarimana's army and Interahamwe militia.
Many fled Rwanda after they were routed by President Paul Kagame's troops following the genocide. They regrouped in DRC to plot a return to power in Kigali, forming an armed group that eventually became the FDLR, and have remained in eastern DRC ever since.
Former DRC President Laurent-Désiré Kabila formed an alliance with the FDLR to battle Kigali's influence in eastern DRC after 1998. But Kabila's son Joseph, the current DRC president, allowed Rwandan troops to enter Congo in 2009 and chase the FDLR.
Widespread war crimes
FDLR fighters have been responsible for widespread war crimes in DRC, including ethnic massacres, mass rapes, and forced recruitment of children, campaigners claim.
The group's military commander, Sylvestre Mudacumura, a Rwandan who has commanded the FDLR's military forces since 2003, is sought on an arrest warrant from the International Criminal Court (ICC) for war crimes committed in the eastern region.
UN security sources estimate the number of FDLR active fighters has dwindled to around 1,000 - 1,500, down from 6,000 in 2009, as a result of military pressure and demobilisation efforts.
However, the group continues to attack civilians in eastern Congo, often in alliance with Congolese Hutu armed groups, such as Michel Rukunda's Republican Federalist Forces (FRF), a South Kivu militia claiming to defend the interests of the Banyamulenge (Congolese ethnic Tutsis) and some Mai-Mai groups. FDLR has an armed wing, FOCA (Forces Combattantes Abacunguzi), also active in South Kivu.
Check out our Flipboard magazine - Who's who in the battle for DRC by IBTimes UK
In this series on the Democratic Republic of the Congo, IBTimes UK takes a closer look at the eastern regions of South and North Kivu where civilians are still at the mercy of armed groups and the Congolese armed forces, who have all been accused of committing serious war crimes.