Darfur rebel leader vows attrition war for Sudan

Ibrahim's close family ties with the powerful Chad-based Zaghwa tribe has bolstered his ranks and military capabilities, especially as relations have declined between Sudan and its western neighbor.

Sudanese President Omar al-Bashir has accused Chad of being behind the weekend attack and warned that his government reserved the right to retaliate. Sudan's state television claimed Ibrahim had asked for Chad to send a helicopter to evacuate him.

Chad's government, meanwhile, announced late Monday that its border with Sudan was closed. But the 600-mile border runs through some of the most inhospitable and remote countryside in the world and armed groups have long passed across it with impunity.

Experts said Ibrahim's advance to the edge of Khartoum was meant to bring the Darfur war to the heart of the regime's power base and force Sudanese to confront the conflict's festering humanitarian wounds, with at least 200,000 dead and 2.5 million people forced from their homes.

The question remains whether Ibrahim can support his boast to harass Sudan's armed forces the length and breadth of the vast country.

"I would be very surprised if this didn't put Khartoum in a continuous state of alert," said Eric Reeves, a Sudan expert at Smith college. "But I don't believe this is a military strategy that really will take it to Khartoum in the long run, and I think the reprisals are going to be ferocious."

Alex de Waal, a British expert on Sudan, described Ibrahim's advances as a "bid for power." He said the rebel leader might want to keep up the pressure on the regime, but was unlikely to be able to withstand the response.

"I think it was a miscalculation," he said. "The majority of Darfur rebels don't share that ambition ... They want peace for their places rather than wanting power in Khartoum for themselves."

Ibrahim's group claims it has thousands of fighters, but most experts believe the number is in the hundreds, making pitched battles like the clash in Omdurman an expensive proposition.

The movement does not lack for military supplies, however, and observers have seen JEM fighters with heavy weapons such as rockets and anti-aircraft guns. AP reporters along the Chad-Sudan border also have seen Ibrahim's fighters operating on both sides of the frontier.