The sudden escalation in the long-simmering tension between Sudan and South Sudan is something neither country can sustain without inflicting serious hurt on their respective populations. The Comprehensive Peace Agreement (CPA) made South Sudan the world's newest country in July 2011, but disputes continue over provinces such as South Kordofan in the Nuba region, Abyei on the border, and Blue Nile. There are also tensions over oil; landlocked South Sudan's pipelines run northwards through Sudan, but it has 75 per cent of the former unitary country's oil reserves and has closed down further supplies, possibly because transit fees were in dispute. The latest fighting has seen the number of refugees in the South rise to 100,000, almost all of whom are already at risk in the fierce dry heat, with severe flooding and water-borne diseases awaiting them when the rains start in a few weeks' time; 30,000 more have fled to Ethiopia. Recent refugees tell of air attacks ordered by President Omar al-Bashir's government in Khartoum, and the Southern President Salva Kiir, during an official visit to China, announced that Sudan had declared war on his country, though he himself had presided over an attack on Heglig in the second week of April; 35,000 civilians are on the move as a result, despite the fact that Juba has now withdrawn its forces. In all this, it is easy to forget the two million who fled their homes in the western province of Darfur.

As so often, the key problems are political. The CPA left the status of South Kordofan and Blue Nile subject to referenda, but those are yet to be held. Secondly, Khartoum had neglected Kordofan for years, mainly because a substantial proportion of its population are Christians or have their own strand of Islam; the province had received no benefits from its oilfields. A rigged 2011 election there led to an uprising, followed by Sudanese reprisals, which were also inflicted on Blue Nile. Worse still, Southern militias are operating in Sudan, and vice versa. In this cauldron of mutual fear and violence, international intervention can achieve little. China, which buys oil from both sides, has long refrained from interference in the internal affairs of its African trading partners. The African Union (AU) and the United Nations Security Council have called for hostilities to cease, but neither side is willing to listen. If there is hope, it lies in the fact that Egypt had a hand in the South's withdrawal from Heglig; the AU, possibly through Egypt, might be able to put enough pressure on both sides to cease their violence. The AU, however, must not stop trying to reach a settlement.

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