From the Guardian, writer Julie Flint gives us this assessment of this truly ugly conflict.
The fighting has significantly increased the chances that the Comprehensive Peace Agreement (CPA) that ended the civil war six years ago will collapse, reigniting a north-south war and ending all hopes of peaceful partition when oil-rich South Sudan formally declares itself independent on 9 July.
Many Nuba fought alongside the southern rebels of the Sudan People's Liberation Army (SPLA) in the 22-year war. As black Africans within the Arabised north of Sudan, their hope was that the "New Sudan" promised by the SPLA would end their marginalisation and win respect for Nuba languages, religious observances and culture. The war that began in the 1980s in the Nuba region of South Kordofan was not just a footnote to the war in the south, it was a civil war in its own right, a deep-rooted indigenous rebellion that prompted a declaration of jihad by the Khartoum government in January 1992. Villages were burnt, livestock raided, food stores destroyed and hundreds of thousands of Nuba forced into "peace camps". But the Nuba were short-changed in the CPA. It denied them self-rule and, crucially, did not specify what would happen to the 30,000-strong Nuba rebel army enrolled in the SPLA.
On 5 June, as the Sudanese government army prepared to "control" – disarm – Nuba fighters, fighting erupted in South Kordofan's capital, Kadugli, and spread quickly across most of the region. The battle for Kadugli became a street-by-street war of attrition: Khartoum piled in brigades of regulars and irregulars, and the SPLA relentlessly mortared the army's divisional headquarters.
UN reports seen by the Observer state that "human rights abuses are commonplace and part of the strategy" in the new Nuba war. There are "door-to-door searches, presumably for SPLA elements"; "wide-scale exactions against unarmed civilians with specific targeting of African tribes"; looting of relief offices and warehouses; and "sightings of cattle-trucks with people sitting on their floors, with sentries guarding them".
"They take the young men," one official said. "Are they going to detain them and feed them and give them water for months? I don't think so."
Four days into the war, the United Nations Mission in Sudan (Unmis) warned in an internal report that a humanitarian crisis was already developing "of a magnitude that Unmis… is not sufficiently prepared to counter and the UN agencies are unprepared to deal with".
On Thursday the Nuba leader, Abdelaziz Adam al-Hilu, told African Union (AU) mediators frantically crafting a ceasefire agreement that more than 3,000 people have disappeared – either killed or their whereabouts unknown – "because they are Nuba or belong to the SPLA". He said 400,000-500,000 have been displaced, in a population of approximately 2.5 million, and more than 50 towns had been bombed.