Saturday’s battle in the streets of Omdurman was a defeat for the prospects of peace, democracy and human rights. The calculations of the leadership of the Justice and Equality Movement are puzzling–the attack looks much like an act of reckless military escalation, bold and daring no doubt, but possibly suicidal. But it would be surprising if JEM did not have other cards to play””possibly short-order attacks on al Obeid, the Meroe Dam or al Fashir.

The attack was a humiliation, for Sudan’s security and military chiefs. That is reason for worry. The raison d’etre of this government is security, and its failure to protect the capital has rocked its credibility. The government will not feel comfortable until it has evened the score. Despite their failure to stop the attack, the security and military leaders will now make the running. Also the fact that the JEM attack was repulsed by the forces of the regime’s core security institutions””National Intelligence and the Central Reserve Police””gives the hardliners the upper hand in what happens next. There will certainly be an internal reckoning within the upper echelons of the National Congress Party and the security services. But first, the regime will pursue the military option without compromise.

Khalil Ibrahim is a Darfurian but this war is not about Darfur. JEM is fighting for N’djamena and Khartoum. In part, the offensive is Chadian President Idriss Deby’s reply to the Chadian rebel attack on N’djamena in February, backed by Sudan. Khalil has dismissed the various efforts at a revived Darfur peace process over the last year, and has recently argued that JEM is the only force that is fighting the government and therefore the only one that should be represented in any talks. On Saturday, Khartoum dismissed any prospects of peace talks: there is fighting to be done first. A real peace deal between Sudan and Chad might have prevented this weekend’s debacle””now it is too late.

Spokesmen for JEM have said that they are fighting for the CPA and its fair implementation, but most people who have followed JEM’s politics consider this no more than a tactic to win the support of Southerners who would otherwise distrust JEM’s Islamist origins, its fierce opposition to Southern separatism and the Chadian fingerprints on its operation. JEM’s manifesto speaks of democracy and human rights””justice and equality no less””but its putchist strategy is the antithesis of compromise, democratic politics and civil liberties. Both the Omdurman attack and the inevitable government response imperil Sudan’s shaky path to democratization and the South’s aim of exercising the right of self-determination. First Vice President Salva Kiir Mayardit saw these dangers when he spoke out against the attack.

The three towns of Khartoum, Omdurman and Khartoum North have enjoyed a remarkable social peace during the last quarter century of war. There has been everyday racism and discrimination but astonishingly little violence. That coexistence may now be in jeopardy. For many Khartoum natives and people of the riverain north””the awlad al balad””JEM’s attack was an assault on their hitherto peaceful and prosperous territory. It was a shock and a horror and many are rallying to the government. Opposition politicians from the north hope that their voices of moderation may help prevent pogroms against the Zaghawa and other suspected JEM supporters and keep alive the prospects of elections next year.

By contrast, for many Southerners, Darfurians and people from Sudan’s other peripheries, there was unconcealed glee at the evidence fear displayed by government’s leaders, and a wider feeling that at long last the nation’s elite was learning the reality of war””the chickens of regional inequity were finally coming home to roost.

Amid the near-certainty of a government crackdown on suspected JEM sympathizers, there is the worrying possibility of a polarization of Khartoum society and politics along regional-ethnic lines. Perhaps this is what Khalil Ibrahim, one of the authors of the Black Book, hoped for when he planned the assault””a blow at the national capital might so rock the foundations of the state that it would collapse. But if history is anything to go by, it is more likely to ignite destructive cycles of violence in the peripheries themselves. In this case, the bloodshed is most likely to begin in Kordofan and the cities of the centre and east where there are large numbers of Darfurian migrants. And we may see new attacks in north Darfur as well.

There were many reasons to be worried for Sudan last week. After the weekend’s battle of Omdurman, there are graver reasons still.