KINSHASA, Democratic Republic of the Congo - There was unexpected news in early November from the Democratic Republic of the Congo (DRC), which has endured two decades of fighting in what has become Africa's deadliest conflict: The M23 rebel group, responsible for numerous atrocities since its inception in April 2012, had been defeated. The M23 was the latest in a succession of armed groups led by ethnic Tutsis in eastern Congo with backing -- weapons, ammunition, recruits -- from neighboring Rwanda. It crumbled after Kigali, facing Western criticism and aid suspension, did not offer the group the same military support that it had in the past during new fighting in October. The Congolese army and the United Nations' new African-led intervention brigade, with its mandate to carry out offensive operations, quickly took control of one rebel stronghold after another. On Nov. 5, the M23 announced it was laying down its arms. This is a significant development, especially for those who have lived under the M23's oppression for the past year and a half. It has prompted over 1,000 combatants and leaders from various armed groups, worried they might be new military targets, to turn themselves in to the government or U.N. But it is by no means the end of Congo's brutal story. M23 leaders with long records of serious human rights abuses -- for whom the Congolese government has rightly ruled out any amnesty or integration into the army -- are still at large. Most have fled to Uganda and Rwanda, and they could form a new armed group if they are not arrested and brought to justice. Just as concerning, however, is that much of Congo's east remains under the control of other armed groups who filled a security vacuum left when Congolese forces turned their attention to the M23 rebellion over a year ago. These groups prey on civilian populations: killing, raping, extorting illegal taxes, forcing children to become soldiers, burning villages, and ill-treating those who resist them. Most have taken advantage of and manipulated existing ethnic tensions in an effort to gain control of land and mineral resources, including gold, tin ore, and coltan (widely used in electronic devices). Their alliances, leadership structures, and even names keep shifting. Some have allied with or received support from the Congolese army -- itself guilty of perpetrating atrocities, including rape, arbitrary arrests, and the mistreatment of suspected M23 collaborators. The Congolese government and the U.N. have said one of their next main targets is the Democratic Forces for the Liberation of Rwanda (FDLR). Many members of the FDLR -- which, after earlier iterations, formed in 2000 in opposition to the government in Kigali -- are Rwandan and ethnic Hutu. Some of them participated in the genocide in Rwanda in 1994, which claimed more than half a million lives. Others, however, were too young at the time to take part in the horrific violence. Some were born in Congo after the genocide, to Rwandan refugee parents; others are Congolese recruits. The FDLR has committed numerous abuses against Congolese civilians. Gen. Sylvestre Mudacumura, a Rwandan who has commanded the FDLR's military forces since 2003, is already sought on an arrest warrant from the International Criminal Court (ICC) for war crimes committed in eastern Congo. According to the ICC, he is allegedly responsible for "attacking civilians, murder, mutilation, cruel treatment, rape, torture, destruction of property, pillaging and outrages against personal dignity." The fight against the FDLR has been inconsistent: In late 2008, the FDLR was estimated to have at least 6,000 combatants, controlling large areas of North and South Kivu provinces, including key mining areas. For years leading up to that point, the Congolese government had turned to the FDLR for support in its fight against Rwandan-backed rebel groups and the Rwandan army. This shifted in early 2009, when Rwanda and Congo made a deal: In exchange for Rwanda's assistance in removing the threat posed by another armed group, the National Congress for the Defense of the People, Congo's President Joseph Kabila permitted Rwandan troops to conduct joint operations with the Congolese army against the FDLR. The Rwandan army left after just one month, but Congolese forces, together with the U.N. peacekeeping mission in the country, continued military operations against the FDLR. The U.N. also increased its efforts to encourage FDLR combatants to demobilize and return to Rwanda. By early 2012, the FDLR was much weaker and its number of fighters had decreased substantially. Yet after the M23 rebellion began, and the Congolese army and UN re-focused attention on the new threat, pressure on the FDLR waned again. FDLR combatants began surrendering at a lower rate, and the group continued attacking civilian populations, often in alliance with Congolese Hutu militia groups. I spoke to a woman in October who told me that FDLR fighters had rounded up and raped her and more than 30 other women and girls from her village in the territory of Masisi last year. While they raped her, the FDLR fighters told her she was "worthless." She lost consciousness, but she believes she was raped by at least five or six men. The woman also said that three girls from her village, ages 7 to 11, died after several FDLR fighters gang-raped them that same night. Defeating the FDLR will not be easy: Its members, which have faced little government or U.N. pressure for months, are scattered in small groups across a vast territory, and they are experts at disappearing into the forest and blending in with civilian populations. Past military operations against the FDLR have also spurred the group to carry out large-scale attacks on civilians. Several other Congolese armed groups claim to be protecting the population from the FDLR. One is the Raia Mutomboki ("outraged citizens" in Swahili). This is a loosely organized network of former fighters in other militias, demobilized Congolese soldiers, and youth who have armed themselves largely with machetes and spears. The Raia Mutomboki have killed hundreds of civilians since mid-2012: Often purposefully avoiding direct clashes with the FDLR, they have instead focused their attacks on dependents of FDLR combatants, Hutu women and children who are refugees from Rwanda, and Congolese who are ethnic Hutu. Among the Raia Mutomboki's victims is Ernest*, a 12-year-old boy. When I met him late last year, he told me how the Raia Mutomboki had attacked his village in Walikale territory in August 2012. He said the combatants, shirtless and wearing traditional raffia skirts, entered his village, beating on drums and shouting out that ethnic Hutu civilians should leave the village. Ernest and his family -- who are Hutu -- quickly fled and hid in a thicket of reeds on the outskirts of the village. They thought they were safe, but the Raia Mutomboki combatants found them and proceeded to hack most of the family to death with machetes and spears. Ernest had been carrying his baby niece on his back, and when the Raia Mutomboki killed her, Ernest was covered in her blood, so the attackers assumed he was dead, too. After the attack, he had made it on his own to a displacement camp in a neighboring village several miles away. Ernest spoke in a soft voice, staring at the corner of the ceiling and fidgeting his hands. He told me the names of those he lost that day: his mother, his father, his four brothers and sisters, his aunt, his uncle, and four little cousins. Another militia allied with the Raia Mutomboki and currently opposed to the FDLR -- although it previously collaborated with the group -- has been responsible for some of the most brutal attacks on civilians in recent months. It is led by Ntabo Ntaberi Sheka, a warlord wanted on a Congolese arrest warrant for crimes against humanity. Made up mostly of ethnic Nyanga combatants, Sheka's militia has killed, raped, and mutilated scores of ethnic Hutu and Hunde civilians in western Masisi and eastern Walikale territories. A Hutu woman named Janine and some of her grandchildren escaped an attack by Sheka's militia in late September. Janine was going to her farm to look for food when militia fighters grabbed her and demanded money. She gave them what she had, and as they were counting the money, she managed to escape. She hid in the forest and soon heard gunshots coming from the direction of her village. When she went back the next day, she found that 11 of her family members and neighbors had been killed. Her eldest daughter had been shot in the head, and the daughter's six-month old baby had been stabbed multiple times in the chest, head, back, and ribs. Janine said that when she found him unconscious next to his mother's body, he had lost a lot of blood and was close to death. Janine and others took him to the hospital in the town of Bibwe, at least a seven-hour walk up and down several steep hills through the forest. Janine was holding the baby when we spoke. She said she was worried because he wasn't getting milk, and she didn't know how she'd care for all her orphaned grandchildren -- there are now 10 -- on her own. In the wake of defeating the M23, the Congolese government and the U.N. must address the threat posed by groups like the FDLR, the Raia Mutomboki, and Sheka's militia. This should include efforts to encourage combatants to disarm voluntarily, restore state authority in areas controlled by armed groups, and, in the case of the FDLR, to arrest leaders wanted for war crimes and crimes against humanity. To date, however, such efforts have been insufficient. Little has been done to curb abuses or investigate, arrest, and prosecute those most responsible for them. The government also has no official program for disarmament, demobilization, and reintegration of former combatants. In the past, some combatants have gone to regroupment sites to await such a program, but many gave up on waiting and returned to their militia groups. This is especially worrying given the recent wave of fighters turning themselves in after witnessing the M23's demise. For these defections to be meaningful, the Congolese government, with international support, must act quickly to step up demobilization and reintegration initiatives. Otherwise, whatever improvements in security the M23's surrender may have brought will be short lived -- and the road toward peace will remain as long as ever. Pseudonyms were used for the names of victims and witnesses mentioned in this article for their protection.