"I don’t know why Sudan is not ashamed when they are saying this. I’m surprised," says Maj. Gen. Jagod Mukwar, a heavyset man who is the Nuba rebels’ top commander on the ground. He spoke at his headquarters, accentuating points with a hearty laugh.

"I belong to Sudan,” he says. “I’m fighting because I need my rights. My people are marginalized."

Sudan’s demand, considered unreasonable by diplomats, is connected to the insignia still sewn on the sleeves of many rebels here: the South Sudanese flag.

For years, that was the flag of the Sudan People’s Liberation Movement, the rebel group that won South Sudan’s independence in 2011. Most of its insurgents were South Sudanese, but a sizable chunk came from areas that remained inside Sudan after separation. Sudan’s Nuba formed the largest section of that group, and, as war lore has it, the best rebel fighters.

Under the 2005 peace accord, brokered by the U.S. government, the Nuba were part of the southern army for the six-year peace period, and, as South Sudan re-armed, they did, too. When South Sudan became independent, it allowed the Nuba to keep their arms and continued paying their salaries, even though they lived north of the border.

And that, the rebels say, is all they needed. Now, they capture most of their arms directly from the Sudanese military, though some fraction appears to be coming from Uganda.

Events here back up rebel rhetoric that they are winning this war. Sprawled under the shadow of hills and abandoned huts, in sight of Kadugli, were remnants of rebel victories. A mid-December government offensive lasted only a few hours after the rebels ambushed a flanking force, destroying one Soviet-made T-55 tank and capturing the other four. Two days later, the rebels counterattacked, pushing the government forces nearly back into Kadugli, capturing another tank and destroying another. Left behind were only trenches, scattered munitions and the dead.

The Sudanese government’s one clear advantage, air power, seems to be not much of one. The rebels whisked their captured tanks and other booty – including two white armored personnel carriers and several trucks – a few miles behind the frontline, parked under the sparse savannah tree cover.

For days, Sudanese warplanes, Soviet-era Antonovs, circled overhead attempting to destroy the lost equipment, but they failed. One day, an Antonov circled for more than an hour, bombing every 15 minutes. The bombs, dropped crudely from a back hatch, burst harmlessly into a mountainside more than a kilometer away.

Several days later, an Antonov could be seen circling again. The rebels opened fire with a truck-mounted anti-aircraft gun. Smoke puffed from the plane’s tail, and it moved off without dropping a bomb. The plane later crash landed in the bush, said the rebels, who claimed to have found the wreckage site.

Sudanese officials accuse South Sudan of continuing to back the rebels.

The United States, South Sudan’s most important ally, has pressured South Sudan for more than a year to cut military ties to the Nuba Mountains rebels, fearing more instability in the region. On at least three occasions, President Barack Obama personally appealed to Kiir to end cross-border activities.

Both South Sudan and the rebels say South Sudan is no longer providing materiel or salaries to the Nuba rebels. But South Sudan has offered one ongoing gift, an open border that provides the rebels with their only link to the outside world. Juba, South Sudan’s capital, is a regular stop for rebel leaders.

There is evidence the rebels have a new foreign patron: near the frontline, four munitions crates carried the tag of the Ugandan Ministry of Defense. Ugandan President Yoweri Museveni and Sudan’s Bashir share a long personal animus.

Sudan, too, is receiving outside help. Among the bounty captured by rebels were two sophisticated anti-tank guided missiles from China that, according to the package markings, were part of a recent shipment of 450. The rebels said it was the first time they had seen the missile.

Sudan seems desperate to counter the insurgency.

Sudan’s frontline force is increasingly young and inexperienced, and ID cards show some are college students, the rebels said. Along one boulder outside Kadugli, eight dead bodies lay crumpled in a row. One carried a certificate for a paramilitary government militia relied on heavily during the old war, the Popular Defense Force, which recruits by preaching jihad – even though many of the Nuba Mountains fighters are Muslims, also.

At the beginning of the war, the Antonov bombs blew massive craters. Now, the bombs are more deadly, blasting out shrapnel low to the ground and leaving only shallow indents behind.

So strong are the rebel positions, though, that life in the rebel-held countryside continues on now without much fear of the enemy, except for the incessant buzzing above – and, after a year and a half, even that effect is waning.

"We don’t fear. It’s normal for us now. It has been bombing all day," said Jalila Akamalam as she winnowed out the chaff of peanuts in the stuffy Sudanese wind even as a warplane hummed above.