Once they have stopped the fighting now raging in the Burundi capital Bujumbura, regional peace brokers will face another unpalatable reality.
They will have to unpack the hard-won Arusha Agreement in order to bring the two major rebel movements into the process.
Pierre Nkurunziza, leader of the Forces for the Defence of Democracy (FDD), has said as much. The ceasefire he signed on December 2 was hailed as a breakthrough. But it has never been honoured because Nkurunziza feels excluded from the Arusha process.
Agaton Rwasa’s National Liberation Front (FNL) has never accepted the Arusha process that is now nominally more than halfway along its path of bringing democratic elections to Burundi.
Both Nkurunziza and Rwasa were excluded from the original negotiations designed to end the fighting that has cost 300 000 lives.
When it became clear that without the rebel leaders there could be no peace, they were pressed to join the process. They were expected to accept earlier decisions made without them. These include the sharing of power between the Tutsi minority led by Jean-Pierre Buyoya and the Hutu majority led by current President Domitien Ndayizeye.
Nkurunziza and Rwasa both reject Ndayizeye as a collaborator and insist their Hutu fighters should be the rightful participants in any power-sharing arrangement.
Rwasa has made his point more dramatically than military observers thought possible. His attacks on Bujumbura this month have left nearly 200 dead. They involved close to 4 000 rebel troops — far more than he was credited with commanding.
Conflict analyst Jan van Eck, who left the capital earlier this week, said battles involving tanks and helicopter gunships forced him from his house in the hills above Bujumbura.
He was among 40 000 people driven to seek shelter in the city.
The rebels cut off access to the city, already limited by the hills on one side and Lake Tanganyika on the other. This has prevented government forces from sending in reinforcements.
The rebels are mainly attacking five military camps within the capital. They are clearly targeting the homes of political leaders already drawn into the peace process.
Reports said child soldiers as young as 11 were found among the 28 rebel corpses. Driven back by day, the rebels are moving even further into the city at night. The fighting is being done exclusively by the FNL, although some reports say the FDD is assisting with supplies.
The battalion of South African troops in Bujumbura continues its task of protecting the politicians involved in the transition process.
The South Africans are spread through three bases in the capital and have not been involved in the fighting. When they are rotated next month, they will be replaced by two battalions that will take on a peacekeeping role.
This process is, however, dependent on the arrival of a battalion of Ethiopian troops and a company of soldiers from Mozambique.
Deployment of these fresh African troops depends on financial aid from the United States and Britain. President George W Bush was reportedly surprised to hear this during his visit to Africa last week. He promised to clear up what was obviously a bureaucratic blockage.
The African forces are assigned the task of getting an effective ceasefire into place and creating the other conditions necessary for the deployment of a United Nations peacekeeping force.
The summit of regional leaders in Dar es Salaam on Sunday will have to face the reality that the renewed fighting has made chances of UN military relief even more remote.
South African Deputy President Jacob Zuma hopes that Nkurunziza, and possibly even Rwasa, will be involved along with Presidents Ndayizeye, Benjamin Mkapa of Tanzania, and Yoweri Museveni of Uganda.
Museveni, who saw Zuma earlier this week, has said that Burundi now requires a military solution. These leaders will understandably cling to the Arusha agreement as the basis for further progress.
This accord, won after years of negotiation involving both the late Julius Nyerere and Nelson Mandela, is effectively all they have. By refusing to meet rebel demands for the process to be reopened, they risk losing everything.
The political mood in Bujumbura, says Van Eck, varies widely. “On the one side is the bitter hardline view that the new fighting is being waged by Hutus responsible for the 1994 genocide, who should be crushed because this is the end of the process.
“On the other there are people who say we have to do something more dramatic to restore and save the process. If this means making concessions on Arusha then so be it.”
The summit in Dar es Salaam will not simply be able to patch over the problems with the Arusha process.
The rebels have made their point that they have to be accommodated and that they must be given some say in how this is done. If leaders at the summit are not prepared to accept some new analysis, the whole peace process could be dead.