FACTBOX: What next after rebel attack on Sudan's capital?

(Reuters) - Below are answers to some key questions about the Darfur rebel attack on Sudan's capital.

WHAT'S HAPPENING ON THE GROUND?

The sound of gunfire continues on the western edge of the suburb of Omdurman, across the River Nile from Khartoum. There have been reports that the Justice and Equality Movement rebels are sending reinforcements to back up a first assault that was repelled by government troops, but sustaining a fighting force over 600 km (400 miles) from rear bases is likely to prove difficult over time. President Omar Hassan al-Bashir's government has extended a curfew indefinitely, saying it wants to track down pockets of rebels in the city.

HOW SIGNIFICANT IS IT?

Regardless of whether the rebels succeed in overthrowing the government, the psychological importance of the attack is huge. Khartoum has been able to live isolated from violence for decades while the Arab-dominated central government's forces have battled rebels from the regions on the peripheries of the vast state. The government's failure to stop the rebels reaching the capital is a blow to both the administration and the prestige of the army. For the Justice and Equality Movement (JEM) rebels, it is a boost for their credibility at a time Darfur rebel movements are increasingly fractured.

WHAT IF THE ATTACK IS DEFEATED?

If the government forces break the back of the assault, a backlash against the JEM is almost inevitable. Darfur as a whole may suffer badly too. Officials have said the attack effectively spells an end to chances for peace talks with JEM. That could further complicate the planned deployment of a 26,000 strong United Nations-African Union peacekeeping force in the region.

Its coffers filled with oil money, Khartoum's government can afford the hardware to escalate the war. But the long term effectiveness of military means to end the conflict is doubtful.

Defeating insurgencies is no easy task in the vast land and measures to suppress them tend to further embitter populations against the attacking forces. The success of the Darfuri rebels in even reaching Khartoum could embolden other groups elsewhere.