Who is Laurent Kabila?
Laurent Kabila is the President of the Democratic Republic of Congo, previously named Zaire. When he toppled the former ruler, Mobutu Sese Seko, just 15 months ago, there was great optimism in the country.
But since then he has angered many by outlawing political opposition and closing newspapers. He has also been criticised for failing to implement meaningful reform to restore jobs and deliver some 40 million Congolese from dire poverty.
How did the rebellion begin?
At the end of July President Kabila ordered Rwandan troops to leave the Congo.
Correspondents say he was playing on fears among many Congolese that Rwandans - who were officially in the country to help train the Congolese army - were too dominant.
But in the east of the country, where disillusionment with Kabila's regime was strongest, and the people ethnically-aligned with Rwanda, the move triggered a revolt by a faction of the army.
Why are other countries involved?
President Kabila has blamed the uprising on Rwanda, saying his country has been invaded by foreign forces. He has also accused Uganda of sending troops and tanks across the border.
Both countries deny any involvement.
But correspondents say that in Rwanda's case at least, there is a clear motivation for involvement.
Rwandan troops helped Laurent Kabila come to power in 1997. He also enjoyed the support of Uganda and Angola, both anxious to put an end to Mobutu's corrupt regime.
But these countries may have lost patience with the Congolese president. They each have vital interests in the country's political stability.
The revolt partly echoes the ethnic upheavals which have torn the region since 1994's mass killings of Tutsis by the Hutu majority in Congo's eastern neighbour Rwanda.
An estimated one million Hutu refugees - among them extremist militias who had taken part in the mass killings - poured into eastern Zaire when the Tutsi-led Rwandan Patriotic Front took control in Rwanda.
There was friction between them and the local Congolese Tutsis - the Banyamulenge who, with military backing from the new Rwandan leaders, helped Laurent Kabila oust Mobutu, waging war on the Rwandan Hutu militias in the process.
The latest fighting was triggered when Banyamulenge in Laurent Kabila's army mutinied in response to his decision to expel their allies - troops from the predominantly Tutsi Rwandan army - from Congo.
The Kabila government then accused Rwanda of invading to back their ethnic kin, the Banyamulenge.
How successful have the rebels been?
In a matter of days, rebel forces took control of a number of key towns in the east, and the oil town of Muanda on the west coast.
They quickly advanced to some 300 kilometres from the capital Kinshasa.
Correspondents say the success of the rebel forces suggests that they do indeed have backing from Rwanda, and that the rebellion was well-organised and planned in advance.
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