It's one of Africa's most bitter, if often forgotten, conflicts.
In 2011, South Sudan gained independence from Sudan following a 2005 peace deal that ended Africa's longest-running civil war.
After a referendum, in which an overwhelming majority of South Sudanese voted to secede, Africa's newest country came into being, the first since Eritrea split from Ethiopia in 1993.
But two Sudanese provinces, South Kordofan and Blue Nile, the people of which predominantly wanted to become citizens of the new nation, were excluded from the deal.
The SPLM-N, the northern affiliate of Sudan's People's Liberation Movement (SPLM) in South Sudan, consequently took up arms against the Sudanese government of President Omar al-Bashir, and fighting has continued on and off ever since.
Five years ago, as the war got under way, People and Power sent reporter Callum Macrae to investigate allegations of war crimes committed by the Bashir regime in the region. Last month he went back.
By Callum Macrae
To the northeast of rebel-held territory in the Nuba mountains of South Kordofan, in Sudan, there stands a small symmetrical hill, called Al Azarak. It is surrounded in the rainy season by lush green land which used to provide a good living for the small farmers who lived here. But no longer.
|Al Azarak was the scene of bitter fighting between the SAF and the SPLA [Al Jazeera]
Last April it was seized by the forces of Sudanese President Omar al-Bashir during a multi-pronged offensive designed to overwhelm the forces of the Sudan People's Liberation Army North (SPLA-N) in this central area of the Nuba mountains.
The offensive failed, and Bashir's forces were driven back on most fronts. Their only significant gain was this small hill, which is today the focal point of a tense military standoff. It now seems inevitable that when the fighting season resumes with the end of the rains in a couple of months, the trigger for renewed conflict will be the fight for this rather beautiful little hill.
This forgotten war began five years ago, just a couple of weeks before the partition of Sudan and the creation of the world's newest state of South Sudan. The Sudan People's Liberation Movement in South Kordofan and the Blue Nile had fought with the south in Sudan's long and bitter civil war, but were left in the north after partition.
READ MORE: A journey deep into Sudan's foresaken Blue Nile
The people of these two areas had been promised a public consultation on their future. But instead, Sudan launched a pre-emptive war against them. The SPLA-N fought back. Today they, and their political movement, the SPLM-N, insist that they have no desire to be part of the newly independent South Sudan, run by their bitterly feuding former comrades.
Instead, they say they want the overthrow of Bashir, and the creation of a new, democratic Sudan, in which the decades of discrimination against the Nuban people is ended.
I visited the rebel-held areas in 2011 just as this new war began. In those days, although Khartoum had banned anyone from entering the territory, it was still possible to fly in and land on an improvised runway cut from the bush. Today Bashir's bombs have made that impossible. Instead you must travel illegally, overland, from South Sudan - and in the rainy season that can only be done on quad bikes, a journey that can take the best part of two days.
A war against civilians
This is a cruel war, being fought on two fronts by the Sudanese government. The first is their conventional war with the SPLM North's army, the SPLA-N. That is a war no one is likely to win. The Sudanese Armed Forces (SAF) are far larger and far better equipped than the SPLA. They are also backed by a large number of mercenaries and militias. But the SPLA know the area, are much fleeter of foot and, as they will often insist, they are volunteers fighting for their homeland. After five years of bitter fighting neither side has made significant gains.
But the government's second front is far less conventional. It is a war against civilians. A war fought using bombs dropped randomly on civilian targets, effectively rolled out of the back of old Russian Antonov transport planes.
While we were there we passed schools, hospitals and farmsteads destroyed by government bombing. In Kauda, the rebels' administrative capital, the government hospital has been abandoned after three huge parachute bombs failed to explode. Today they still sit there, embedded in the ground, a permanent, lethal threat. And there is no one who can disarm them because all NGOs, including de-mining companies, are banned by Khartoum.
Further north, on the way to the frontline at Al Azarak, we met Fatana Kodi and Abduraman Alom. Two months ago their four young children were playing with two friends in their small farmstead when two government jets flew overhead and shelled their home. All six children died instantly. There was no conceivable military target in the area. As we arrived we could hear the drone of an Antonov plane above - a constant threat.
|Mothers displaced by the SAF assault on the village of Al Azarak [Al Jazeera]
But there is another tactic that Khartoum is accused of employing, and perhaps the most sinister of all. Locals say the government is deliberately preventing humanitarian access to the area, using the denial of food and aid as a weapon of war.
They also accuse the government of targeting agricultural land - as at the hill of Al Azarak - in an attempt to starve out the population. Locals warn of a growing incidence of malnutrition and epidemics caused by the lack of medical facilities and vaccination programmes.
The Sudanese government rejects these claims completely. A spokesman accused the SPLM-N of "terrorising" the population. He described them as "a branch of the SPLM that misrules South Sudan," and claimed that "arms and salaries are transferred through the porous border".
Last month, Khartoum announced a unilateral ceasefire, describing it as a chance for the SPLA-N "to join the peace process and surrender their arms". It played well internationally but was dismissed as meaningless by people in South Kordofan and the Blue Nile who say fighting is largely suspended during these months anyway because the rainy season renders the government's heavy artillery immobile.
Last week the African Union-mediated peace talks stalled after Khartoum rejected the SPLM's calls on Khartoum to lift its blockade on humanitarian aid and allow access via Ethiopia. The government said the route could be used to supply weapons to the rebels. The SPLM-N, which believes Khartoum would use exclusive controls over humanitarian access strategically as a weapon of war, suggested a compromise whereby 80 percent came via the government and only 20 percent via Ethiopia, but that was rejected.
And so the people of both South Kordofan and the Blue Nile are preparing once again for the fighting to restart. It would mark the start of year six of this forgotten war.
Source: Al Jazeera