TACHUIEN, South Sudan -- A trench dug across a red dirt road marks part of the shifting border this week between Sudan and South Sudan, old enemies whose forces have clashed in recent weeks. Truck-mounted anti-aircraft guns and 107mm rocket launchers lurk underneath the trees. New foxholes have been dug.
America and other nations are trying to stop all-out war from breaking out between Sudan and the world's newest country, but the weather might do more to dampen hostilities. The sky is a low-hanging gray, portending seasonal rains which will turn the earth into mud, impassable to tanks and trucks.
Brig. Gen. Abraham Jongroon Deng thinks the six-month rains will cool tensions.
"They relax and we relax. We wait until December. It will stop the war," Deng told an Associated Press team that visited the front lines.
Lingering disputes over borders, oil and other issues led to heavy battles last month that threaten to re-ignite a decades-long war that ended when a fragile peace was forged in 2005.
Even the rains are unlikely to bring hostilities to a complete halt. Political leaders and some commanders in the southern military – the Sudan People's Liberation Army, or SPLA – note that troops can still march over the soggy ground and Sudan can still deploy bombers, which have been carrying out periodic air strikes.
A military patch on Maj. Gen. James Gatduel Gatluak's sleeve shows the symbol of the 4th Infantry Division, and the reason the stakes here are so high: an oil well spouting black crude. The division is known as the SPLA Petrol Division.
"I expect more attacks from Sudan. Even if they don't come themselves they can send militias or attack from the air. The rain, it can stop the fighting, but not always," said Gatluak whose face is a mask of tribal dots that is a tradition among the Nuer tribe.
In recent weeks, Gatluak's men have shot down two Sudanese aircraft – a MiG fighter jet and a baby-blue unmanned spy plane that Gatluak said appeared to have been from Iran.
When South Sudan broke away and became an independent nation last July, it took with it roughly 75 percent of Sudan's oil industry. Last month, SPLA forces moved into the oil town of Heglig, site of Sudan's last remaining large oil installation. Southern leaders say Heglig belongs to them even though a 2009 arbitration court ruling produced a map that showed Heglig remaining in Sudan, helping the country to cement its claim.
But the south says a foundation stone laid by the British colonial government in 1956 proves Heglig is South Sudan's. Since the stone – if it exists – lies in territory controlled by the Sudan Armed Forces, the claim is difficult to prove.
Sudanese forces advanced on Heglig after the south captured it, and the southern forces fled 10 days after taking it. The new frontline has now been pushed to the south, to Tachuien, a bare spot on a bare dirt road.
About 60 kilometers (40 miles) to the southeast is Bentiu, the capital of Unity State. Bentiu has a single paved road. Large streetlights hang overhead but they haven't been lit since South Sudan shut down its oil production after it accused Sudan of stealing its oil.
Life appears normal in Bentiu, even though its lone bridge – a strategic military crossing point – was targeted by Sudanese bombs last month that barely missed their target. Girls with baby-blue UNICEF backpacks walk the streets as U.N. vehicles rumble past. Trash – plastic bottles, mostly – is strewn everywhere. Six busted-up deep freezers are piled atop one another at one intersection.
A handful of fighters from Sudan dart around in camouflage trucks. Chianjiek said they may be a part of an alliance of rebels known as the Sudan Revolutionary Front. Sudan has demanded that South Sudan stop assisting northern rebels. Their presence in Bentiu underscores how both sides support shadowy groups of militants to carry out fighting by proxy.
The United Nations Security Council has told Sudan and South Sudan to stop fighting and return to talks or risk economic sanctions, something neither side can afford now that their respective oil industries have been crippled by the south's January shutdown. South Sudan can no longer sell oil, while Sudan is losing the transit fees it charged the south for moving oil through the northern pipelines.
Both sides have indicated willingness to follow an African Union plan backed by the U.N. that demands a cessation to fighting and a renewal of talks, said AU spokesman Noureddine Mezni.
South Sudan's oil fields – which provide 98 percent of the country's budget – are now eerily quiet. The Indian and Chinese engineers who ran the south's fields left weeks ago. Powerless high-tension lines run beside a dusty road, past mud and straw huts that provide precious shade from the scorching sun in the almost treeless, stark landscape.
Somewhere to the north is the foundation stone, southern leaders insist, though even if the existence of the marker is proven it is unlikely to convince Sudan to give up its territorial claims.
"The stone is somewhere in Kansana. We were in Kansana until late 2007. We didn't know Khartoum was going to claim that place to be the north's," said Michael Chianjiek, the deputy governor of Unity State.
In an attempt to show that Heglig is the south's, Manyieuu Dak, the security adviser for Unity State, said that in his previous position as state health minister his workers carried out vaccinations in the Heglig region as recently as 2000.
A former local politician said that when the south's forces captured Heglig, they "didn't burn the oil because it's our place."
At the headquarters of the 4th Infantry Division outside Bentiu, Gatluak told a reporter on a recent day that all was quiet along the border. He noted that tanks can't cross the ditch at Tachuien, which was dug by Sudanese forces.
He sat under a tree outside his office. A baboon wandered by and troops reached out and petted it. It was a tranquil scene, but Gatluak does not think it will last.
Even if the situation quiets with the coming of the rains, they will end after a few months. The ground will dry up. Tanks and troop transport trucks will be able to move again.
One year from now, Gatluak predicted, the war will be bigger and more intense.