A little background.


Sudan has been at war with itself for almost its entire post-colonial history, starting in 1956. After decades of fighting for independence from the north, southern Sudan seceded on July 9, 2011, and became the Republic of South Sudan, six months after nearly 99 percent of the region’s voters approved the split in an internationally backed referendum.

The south’s departure did not put an end to conflicts. There were many unresolved issues, and Sudan and South Sudan soon began squabbling bitterly over how to demarcate the border and share oil profits. (The conundrum of the two Sudans is that both countries are extremely dependent on oil, but while the export pipelines run through the north, the bulk of the crude oil lies in the landlocked South, which seceded from Sudan last year after decades of guerrilla war.)

Complicating things even further was a fierce rebellion in the Nuba Mountains, which lie just across the border in Sudan. The Nuban fighters had been close allies of the southern rebels, and there was evidence that South Sudan’s new government was covertly supplying the Nubans with money, tanks and militia fighters. At the same time, Khartoum seemed to be covertly arming ethnic militias in the south that had killed thousands in the past few years, making a mockery of the South Sudanese security forces.

In January 2012, after having failed to reach an agreement with Sudan on a pipeline fee, South Sudan abruptly cut off all oil production, beggaring the economies of both countries. Fighting erupted along the border in April, and many people feared that the two sides were sliding again into a war that could ripple across East Africa.

In April, vicious north-south fighting broke out along the border. Despite boasts by Sudan’s president, Omar Hassan al-Bashir, that he had “fertilized the soil with their dead,” South Sudan surprised many by seizing Heglig, one of the last oil fields Sudan still has.

Finally, after the highly divisive oil issue nearly drove the two countries to war, both Sudan and South Sudan reached a deal on oil pipeline fees in early August 2012.

After some not-so-subtle pressure from Secretary of State Hillary Rodham Clinton, who visited Juba, the capital of South Sudan, on Aug. 3, the Southern Sudanese increased the amount they were willing to pay Sudan, which controls the pipelines for export.