Gen Nkunda aimed to target those responsible for the Tutsi genocide
By Peter Greste
BBC News, Nairobi
By almost any measure, it has been a spectacular reversal of fortune for General Laurent Nkunda.
Two weeks ago, he was widely regarded as the key power-broker in the east of the Democratic Republic of Congo.
He had forced the Congolese government into direct negotiations after advancing his troops to the outskirts of the regional capital, Goma.
A seemingly endless conga-line of diplomats and envoys had passed through his headquarters in the town of Rutshuru, begging him to accept a permanent ceasefire and a lasting peace agreement.
When I last saw him, Gen Nkunda was on the veranda of his sprawling farmhouse headquarters, locked in an animated conversation with diplomats despatched by the UN secretary general's special envoy.
Meanwhile, a European Union delegation led by Commissioner for Humanitarian Affairs Louis Michele sipped tea in the lounge waiting for their turn with the uniformed commander.
Capable military leader
Now he is under arrest, captured by the Rwandan troops he once served; his own rebels under the command of the Congolese forces they'd been fighting only months earlier.
Gen Nkunda built his reputation as a loyal and capable military leader in the Rwandan Patriotic Front (RPF) - the rebel force which ended the genocide of 1994, and drove the ethnic Hutu Interahamwe militias out of Rwanda and into eastern Congo.
Gen Nkunda then joined rebels led by Laurent Kabila in the Congo (then Zaire) to topple President Mobutu Sese Seko from power.
More than 250,000 people were displaced by recent fighting
But when Mr Kabila broke with his Rwandan allies, Laurent Nkunda became a commander in another rebel force, the Congolese Rally for Democracy.
That force eventually joined the coalition government and Laurent Nkunda was promoted to general in the Congolese Army.
But he never took up his post, instead forming his own militia, the National Congress for the Defence of the People (CNDP), which he said was aimed at protecting eastern Congo from the remnants of the Interahamwe.
The coincidence of goals for both Gen Nkunda and Rwanda - targeting those responsible for the genocide - led many to assume he had the covert backing of his former comrades in the RPF.
That is also why his arrest by the Rwandans seems such a stunning turn-around.
His greatest mistake may have been the military offensive he launched last October, pushing his troops to the edge of Goma, and forcing more than a quarter of a million people from their homes in the process.
The attack humiliated the Congolese army, and appeared to trigger a cabinet reshuffle in Kinshasa where President Joseph Kabila (Laurent Kabila's son) scrambled to shore up his own political support.
That, and intense international pressure to end the conflict, opened the space for a new relationship between Kinshasa and Kigali.
The first signs of trouble for Gen Nkunda emerged earlier this month, when his chief-of-staff, Gen Bosco Ntaganda, announced that the group's leader had been relieved of his duties because "of a failure of political leadership".
Then Gen Ntaganda announced his forces would work with the Congolese army to fight the Hutu militias, and eventually integrate into the army.
The Congolese army fought Gen Nkunda's rebel troops
And in a final blow, the Congolese government invited about 4,000 Rwandan troops to join them in their own bi-lateral push against the Hutu forces.
It is not entirely clear what will happen to Gen Nkunda now.
The Congolese government has indicted him for war crimes, and will almost certainly seek his extradition.
It's less clear whether the Rwandan authorities will be willing to hand him over to their former rivals and risk damaging revelations about their past relationship.
But either way, Gen Nkunda appears to be out of the way, and his forces effectively neutralised.
War not over
All this is, of course, good news for the civilians who have suffered terribly from the fighting. But it doesn't mean the war is over.
In fact UN diplomats have warned that it could even deteriorate in the short term.
The new joint Congolese-Rwandan force is yet to take on the Hutu militias every bit as ruthless as the Lord's Resistance Army which has killed at least 600 civilians in reprisals for a similar multi-national offensive further to the north.
And eastern Congo is - still - a bewildering patchwork of warlords who will scramble to fill the vacuum.
Gen Nkunda's arrest takes one element out of the problem, but it by no means solves it.