Where Sudan seemed to be inching towards a stable partition, now it is speeding towards renewed war. Barely bothering with an excuse, Khartoum's forces seized the contested border region of Abyei late last month. At the weekend, southern forces were warned to vacate the border states of Blue Nile and South Kordofan, with another northern offensive feared.
This is a blatant territory grab by the north in the lead up to the south's independence on July 9. Abyei, Blue Nile and South Kordofan were all granted special status in the peace deal of 2005 that ended two decades of civil war between the north and the south. All three are supposed to hold elections to determine their eventual status - a process that Khartoum seems intent on hijacking.
It's not just that facts on the ground will be hard to change once northern forces have seized military control. The Sudan People's Liberation Movement in Juba has backpedaled as fast as it can, refusing to be provoked by the Abyei offensive, with no interest in restarting hostilities before independence. But where a full-scale retreat from Abyei was possible, Juba will find it difficult to withdraw from other border states with such alacrity, for both strategic and political reasons. It is just a question of how far northern forces can go before they force a war.
Tens of thousands of southerners have fled Abyei in recent days, and there are allegations that the north is moving in tribesmen to take their place. Evidence that civilian homes have been razed suggests possible war crimes - a familiar charge against Khartoum's president, Omar al Bashir, who already faces International Criminal Court charges relating to the conflict in the western region of Darfur.
In a country that has suffered decades of brutal fighting at a cost of some 1.5 million lives, what makes this conflict so troubling is its predictability. The UN, US and EU have long called for direct talks on issues of borders, oil revenue and currency. Mr al Bashir has resisted at almost every juncture.
Peace is still attainable. The African Union's announcement on Tuesday of a demilitarised zone along stretches of contested borders could present a welcome pause in hostilities. The question now is whether joint patrols of contested areas - a key element of the 2005 peace deal - will be ignored going forward as they were in Abyei.
These regions will remain a flashpoint until treaties and elections establish a fixed border. In the meantime, Khartoum's attempts to impose its own puts the entire region at risk.