As the sun set over this desert camp, Pvt. Lambert Sendegeya, an African Union soldier from Rwanda, popped in a tape of music from his country and launched into a series of leg bends. Lt. Eugene Ruzianda peered from his canvas tent and, removing his green beret, joined the evening exercises.

As they stretched, they lamented their daunting task: protecting 80 African Union military observers who are charged with monitoring a rarely observed cease-fire in Sudan's strife-torn region of Darfur, an area about the size of France.

They rattled off the reports of violence they had heard and the instances in which victims had handed them handwritten notes about fighting and rapes. But neither the monitors nor the protection forces have enough vehicles or manpower to investigate, the soldiers said.

"Every night you go to sleep thinking, 'I could do more. We could do more with a better mandate,' " said Ruzianda, also a Rwandan, whose family fled to Congo during a civil war in his country in the 1990s. "I hate it, to see people living like this. There are some things that remind me of our country when people were fleeing. It can be a shock to see it all again. This time, the only comfort is that at least we are here. At least there is something."

These men are part of the generation that survived the 1994 Rwandan genocide, 100 days of violence in which 800,000 people were slaughtered. The Organization of African Unity, since replaced by the African Union, stood by silently while the carnage unfolded. The United Nations, which had a small force on the ground during the bloodshed, also did not intervene.

Now 155 Rwandans, part of a 305-member African Union force, are being asked to demonstrate that Africans can stop African wars. The United Nations, backed by the United States and the European Union, called for the group's involvement in Darfur, its first serious test.

Burned villages smolder across the region. About 1.4 million Africans who were driven from their farms now live in squalid tent cities that continue to swell. Thousands of people have died in the crisis, which the United States has termed a genocide.

The violence erupted in February 2003, when African tribes rebelled against the Arab-led government. The government responded by bombing villages and arming and supporting an Arab militia known as the Janjaweed to put down the rebellion, according to the United Nations and human rights groups. The government has said the Janjaweed is not under its control.

The U.N. Security Council adopted a resolution this month that threatens sanctions against Sudan unless it stops the violence and establishes a commission to investigate atrocities. The council has also threatened to send 3,000 more African Union troops to Darfur if security does not improve.

The monitors and their protectors are key to ending the conflict. Their job is to track violations of the cease-fire by the government and by the African rebels and report them to the union's political wing, which is conducting peace talks between the two sides in Nigeria.

Aid groups say the force's mandate is vague and are pressing for more explicit orders that would allow the soldiers to use force to stop the attacks on civilians.

Sudan's government has said it would reject any role for the force beyond monitoring. In Khartoum, government-owned newspapers are filled with fiery editorials accusing the troops, who represent 12 countries, of bringing HIV/AIDS to Sudan. Other stories have likened the mission to the U.S. invasion of Iraq.

But Sudan's government may not have a choice. Attacks are continuing in villages and around camps, which refugees describe as "prisons without walls," said Louise Arbour, the U.N. high commissioner for human rights, who recently visited the region.

"People cannot return home because they do not trust the government to protect them," Arbour said. "It's clear they need an increased international presence on the ground."

The African Union force, created in 2002, is still in its infancy. The union's chairman, President Olusegun Obasanjo of Nigeria, has appealed for $200 million to buy logistical equipment. The U.S. Senate on Thursday approved a bill providing $75 million for the force.

During a recent visit to a base in El Fasher, Gen. Festus Okonkwo of Nigeria sat in an air-conditioned trailer and listed the vehicles in his tiny fleet: three helicopters and six armored personnel carriers.

"As many more as you can afford to give me, I will take," Okonkwo told a visiting delegation that included U.S. Rep. Jim Kolbe (R-Ariz.), chairman of the House Appropriations subcommittee on foreign operations.

The shortages resonate with the Rwandans.

"We hope and would appreciate the very important help," said Maj. Emmanuel Rugazoora, a Rwandan commander. "We want to solve an African problem. No one should be ashamed to ask for more help where there are people suffering."

Rugazoora encouraged his men to keep working, and not to worry about politics. "Focus on Darfur," he ordered.

"We want to go in deep," said Sendegeya, the private, who grew up as a refugee in Burundi during Rwanda's war. Many of his family's friends, who stayed behind, were killed. "As a Rwandan you feel this should be looked at very carefully and there should be goals," said Sendegeya, 32. "My sentiment is emotional if there is a problem."

There are days when there are not enough cars for all of the monitors to go out, and Sendegeya sits in his tent, cleans up the compound and exercises.

But he said he was glad to be here. "You know, it's interesting because in spite of everything, I feel like I am doing something to resolve the conflict," he said.

Ruzianda, his immediate commander, slapped his friend's back and said he understood.

"Even when I complain, I am very happy to be contributing to this, even a little bit," said Ruzianda, who was a member of the military force that stopped the genocide in Rwanda. "It's different for us."

The Rwandan soldiers, some holding AK-47s, gathered to talk about the good they said they hoped they were doing. Many said they had attended ceremonies back home in April commemorating the 10th anniversary of the genocide.

They talked about the women who attended the ceremonies, many wailing and holding up framed photo collages of the children they had lost. Some of the soldiers mentioned that foreigners descended on their country for the anniversary, but weren't there a decade ago to stop the slaughter. And they spoke about the words inscribed atop the recently opened genocide museum: "Never Again."

One youthful-looking guard, who said he had lost his parents in the genocide, walked away. "I'm going to bed," he said. Another stared bleakly at the ground.

Ruzianda smiled weakly and shrugged his shoulders. "This is my wish: never again. And isn't that what we are proclaiming here? So stop being foolish," he said. "Our continent doesn't need this all over again."

Rwandan soldiers boarded a U.N. helicopter at El Fasher airport last month. About 155 Rwandan soldiers are in Darfur; many survived the genocide in their own country.A Rwandan officer and his troops prepared last month to leave for Darfur, where they now make up part of an African Unity force.