The International Court of Justice has ruled that it is unable to rule on a case brought by Democratic Republic of Congo against Rwanda.
Some 3m Congolese died during the war
The Congolese government accused Rwanda of armed aggression, mass killings, rape, abduction and looting.
DR Congo filed a case in the world court in 2003, after Rwandan troops invaded and occupied part of eastern Congo, as it chased rebel groups.
The ICJ last year said Uganda should pay compensation in a similar case.
Ugandan and Rwandan troops entered DR Congo, alongside each other.
Uganda had voluntarily accepted the court's jurisdiction, unlike Rwanda.
Several African states were involved in the following war, which left 3m people dead.