The ailing president left France for home yesterday, after receiving treatment for cancer. But the rebels said his return made no difference. As Kinshasa buzzes with rumours of a military coup, Laurent Kabila and his victorious rebels plan to make sure that it is they and not the Mobutists who call the final shots of the war.
Although its frontline troops have only just captured Kisangani, 800 miles from Kinshasa, the Alliance of Democratic Forces for the Liberation of Congo-Zaire says it intends to fight all the way to the capital if the authorities there - whoever they may turn out to be - do not swiftly come to terms.
Four months ago, when the rebels emerged from the hills of southern Kivu to capture the frontier towns of Goma and Bukavu, few people took seriously their threat to overrun the entire country. But after the fall last weekend of Kisangani, Zaire's third largest city, it seems possible that the shadowy rebel army can indeed take Mr Kabila, who yesterday visited Kisangani, all the way to Kinshasa if Mr Mobutu or his successors refuse to give up power.
Originally dominated by ethnic Tutsis from the Kivu region, who rebelled last October following government pogroms, the rebels remain a largely unknown, invisible force. Tight controls on movement in rebel areas ensured that few journalists or aid workers have got anywhere near the fighting.
Kinshasa and its allies claim that there is a reason for this secrecy. They allege that the bulk of the fighting is being done by troops from the Rwanda and Uganda veterans of the 1986 war against Milton Obote and of the 1994 campaign that ousted Rwanda's genocidal Hutu regime. Both countries had poor relations with Mr Mobutu, who allowed Ugandan rebels and Rwandan Hutu infiltrators to operate from his territory.
Uganda and Rwanda have consistently denied these claims, but Westerners who were in Rwanda and Zaire during the Kivu campaign last year noted distinct similarities in style between the rebels holding the towns and the well-disciplined fighters of the Rwandan Patriotic Army.
Journalists were present last November when RPA troops attacked across the border from neighbouring Gisenyi, ostensibly to drive off Zairean Armed Forces (FAZ) who had mortared the town. Goma fell to the rebels the same day.
Since then, some of the rebel officers in Goma have been identified as Zairean-born Tutsis who had left Zaire in the late 1980s and early 1990s to join the Rwandan Patriotic Front, then in exile in Uganda.
Whatever the nature of the links between the rebel forces and the Rwandan government, few in eastern Zaire doubt the links are strong.
The rebels' leader, Laurent Kabila - a non-Tutsi whose name was first linked to the rebellion a month after it broke out - has been at pains to show that Zaireans of all ethnic groups are flocking to the rebel cause. He claims to have more than 15,000 men under arms, including numerous defectors from the FAZ.
The source of the rebels' equipment and ammunition is unclear, although they have, as Mr Kabila claims, captured large quantities of both from the FAZ and its allies in the exiled Rwandan Hutu army.
While they have mortars and some artillery pieces, the rebels seem to rely mainly on small arms and the tactics of stealth and surprise perfected by the Rwandan Patriotic Front in 1994.
People in the captured towns have said that the rebels seem to operate in small groups. They often infiltrate at night and the ensuing confusion, together with a few mortar rounds, has usually been enough to frighten off the demoralised, untrained and unpaid FAZ soldiers.
The identity of the commanders directing these tactics remains largely unknown, although Mr Kabila's son is officially credited with leading the capture of Kisangani. Andre Kissasse, who described himself as the alliance's military leader last November, was killed shortly afterwards, reportedly in an ambush.
Whoever Mr Kabila's generals are, they could yet win the war without fighting a battle. Mr Kabila said this week that superior knowledge of the terrain - mostly thick jungle, rivers and swamps - ensured his fighters had little difficulty coping with the 300-odd white mercenaries imported by Mr Mobutu at the beginning of the year.
While some rebel leaders have said the southern city of Lumumbashi is their next objective. Mr Kabila says his men are also acquiring boats for a fresh advance down the Zaire river towards Kinshasa.