As if the fragile Democratic Republic of Congo hadn't already seen enough bloodshed, a leaked UN report now claims that a new rebellion is being fuelled by its neighbour, Rwanda.

The rebel outfit, which calls itself M23, includes many defectors from the Congolese army. It has vowed to "fight to the last man" against the country's government – which in turn has vowed not to back down.

Ordinary people in eastern Congo are already starting to flee their villages; after living through years of unimaginable horror, they know what happens next. And, not for the first time, Rwanda stands accused of fanning the conflict, by training and arming the rebels.

What's really going on here

People tend to think of Rwanda's genocide as a horrifying event which happened in 1994, and since then the country has tried to rebuild itself and heal. That is part of the truth.

What also happened is this: the genocide ended when a Tutsi-led army, led by Paul Kagame (now president of Rwanda), forced the mainly Hutu perpetrators out of the country – and into neighbouring eastern Congo.

There, in a political power vacuum, different militias have killed, maimed and raped, and forced children to do the same. The fighting has claimed over 5 million lives since 1998.

To make matters worse, the UN has several times alleged that Rwanda's government is training and arming rebel groups in the region. Rwanda's purpose, so the thinking goes, is both to keep the genocide perpetrators at bay, and to buy access to the region's mineral wealth. (Rwanda is small, relatively resource-poor and landlocked.)

Rwanda has always vehemently denied involvement, and has very publicly involved itself in negotiations to bring peace to eastern Congo. The latest such agreement involved an amnesty for many of the rebel fighters and their induction into the Congolese army. For a while, this fragile peace appeared to be holding – but now a new breakaway faction has emerged. Here's the first interview with M23 members:

No heroes here

The fighters in this film may try to portray their struggle as heroic, and deny they are using child soldiers or are involved with anyone wanted for war crimes. But the reality is that every conflict in this region has sunk to astonishing depths of depravity: sexual slavery, mass mutilations, and children forced to commit unimaginably barbaric acts.

The Congolese army, for its part, has an appalling record too; as do, sadly, elements of the UN peacekeeping forces stationed in the region. In short, there are no good guys and bad guys here. But there are some lessons to be drawn.

No more convenient fictions

Shamed by their failure to prevent Rwanda's genocide, western leaders have wanted to support the country in its recovery: half of Rwanda's budget comes from foreign aid. And they have wanted to believe its success story of reconciliation, renewal and growth.

Rwanda's economy is indeed growing, violence and crime inside the country is low, it has invested heavily in environmental conservation and it has elections (even if the ruling RPF party wins by ludicrous margins).

Rwanda certainly cannot be blamed for all the violence in eastern Congo. But the worrying evidence that it is contributing to the conflict cannot be ignored. To ignore it would not only mean failing millions of people who have already suffered so much, and are now fleeing their villages, once again. Not only would it condemn the DRC, once again, to possible civil war. It would mean that, once again, the world has failed to learn the lessons of Rwanda's genocide.

Further reading: The Economist review of Dancing in the Glory of Monsters, Jason Stearns' history of the last 15 years of war in Congo.