Najaf, Iraq - Clutching binoculars, the men stand in watchtowers behind razor wire and scan the horizon for threats as squads of their colleagues patrol the desert armed with machine guns.
It is a mission to guard. But, at first glance, what they are protecting doesn't look like much at all.
A black plastic pipe, remarkable for nothing but its unusually large size and the dirt that streaks its sides, snakes over the sand for maybe 300m before burrowing under the earth. Old newspapers and other rubbish line its sides near the high fence that keeps people away.
According to General Hamid Abdullah Ibrahim, commander of the Iraq Oil Police, these sections of pipe that lay above the ground or not far below it, used to be a smugglers' paradise.
This is one of the country's strategic oil pipelines, built in the 1970s by now ousted leader Saddam Hussein and used to transport its most valuable resource to the ports from where it is shipped around the world, bringing in almost of all of the ravaged country's revenue.
In the years after the US-led invasion of 2003, when the country was thrown into utter chaos, much of Iraq's pipelines and other oil infrastructure lay lightly guarded or sometimes not guarded at all, and thieves and saboteurs thrived, siphoning off millions of dollars' worth to sell on the global black market.
The oil police, formed in 2007, was the government's solution. A paramilitary unit of about 30,000 men, it has one task: To protect refineries, tanker lanes and about 7,200km of pipelines.
The job has always been difficult, but it has become much tougher recently. Hamid can tell stories of pipelines blown up, of facilities stormed and of oil police officers killed in the line of duty.
"We have been facing a fierce assault, especially since 2013 and through this year," he told Al Jazeera at oil police headquarters, elaborately-framed maps of petroleum fields hung on the wall behind him. "The enemy's strategy is that oil can be considered a weapon of war for his benefit. So they are trying to halt some important strategic oil pipelines they know will affect the country's economy."
The enemy the general refers to is the Islamic State of Iraq and the Levant (ISIL). A rebel group with momentum on its side, it was formed by members of a now disbanded al-Qaeda affiliate, and has since been buoyed by involvement in the war in Syria, gaining fighters, cash and weapons.
"We need to have more advanced training than we have now and the type of weaponry used by our forces needs to be changed," Hamid said. "Because the enemy is now obtaining advanced and heavy weaponry - they have mortars, RPGs and new assault rifles."
By comparison, Hamid explained, his men are armed only with much lighter weapons.
The specialist unit's headquarters is purpose-built in the country's massive oil ministry compound, famously one of the only buildings that US forces effectively protected from looters after the fall of Saddam, stationing about 50 tanks at every entrance and sharpshooters on the roof.
A busy place, police officers pace its narrow halls and small offices, drinking sweet tea and poring over maps. Inside the main control room, there are eight large maps on the wall, the plastic that frames them daubed with marker pen. Officers man phones from crammed-together desks.
Sometimes they've had to train with plastic guns. They're a long way off [from] being able to properly police the oil fields.
Colonel Khalid Saad cautions that only one map can be photographed, the others classified as secret. He agrees with General Hamid that the oil police are under-resourced.
"We need probably another 10,000 men to operate more effectively," he says.
Foreign security experts, who are often employed to advise the major oil companies who have invested here, agree that the force has been under-resourced and often, they say, poorly trained.
"Sometimes they've had to train with plastic guns," one Western security adviser who regularly works in Baghdad told Al Jazeera. "They're a long way off [from] being able to properly police the oil fields."
At an oil police regional command centre in Najaf, 160km southwest of Baghdad, a squad of about a dozen men run to two pick-up trucks to go out on patrol. Though the location was handpicked by the unit's headquarters for an Al Jazeera visit, uniforms are mismatched and many helmets are ill-fitting.
Several of the oil policemen are wearing formal shoes instead of police-issue boots and one young man is sporting a heavy leather pair of dress shoes with heels and pointed toes.
Iraq's security forces are often under-equipped and, faced with the daily threat of suicide attacks, morale can be low and jitters high. On the road between Baghdad and Najaf, when an armoured oil police vehicle gets a flat tyre, it is hurriedly changed as the gunner in its turret scans the horizon.
The Najaf commander, Colonel Sabah Ali, a man with an easy smile who appears to have a good rapport with his men, echoes the other officers and says he needs more recruits.
"Though we're operating with 50 percent of the resources we need, we get about 80 to 90 percent of the job done," he says. "But if we had more men we could more easily cover this vast landscape. At the moment, we can only rely on roving patrols to try to watch the entire pipeline."
The colonel says his brigade has rarely engaged the enemy. Rather, they rely on intelligence given to them by the local community and on the fact that most of their recruits are drawn from it.
Here, it appears, they have the support of the locals. But it is not so simple elsewhere.
ISIL now holds parts of Anbar province, just an hour's drive west of Baghdad, and it has consistently targeted oil infrastructure there. It is also strong in the north of the country and its attacks last month forced a suspension of exports through northern pipelines into Turkey.
Other anti-government Sunni groups in Anbar, who say they have been marginalised by the Shia-led government, are also attacking pipelines. And, like ISIL, they seem determined to continue.
"What we are doing is that we are defending our identity, we are defending our freedoms and the future," Sunni tribal leader, Kusai al-Issawi, told Al Jazeera. "Since a part of the network of pipelines in this country runs through our land, we deserve to have a fair share from its revenues.
"And because the government is not giving us our rights, and for as long as military operations continue, our only response is to cut off the resources."
The stakes are high. Iraq has ambitious plans to challenge global oil powerhouse Saudi Arabia as the world's top exporter and, were it not for the attacks, it might not be far off that target.
According to government figures, exports reached 2.8 million barrels per day in February, the most oil Iraq has sold on the global market for decades. But since then, with violence chiefly to blame, the amount has dipped again.
The oil police will be expected to stay on the frontline, trying to make sure that trend is reversed. But they will do the job without much from their wish list - heavy weapons, surveillance cameras, rapid deployment teams.
"I have asked for all of these things," General Hamid told Al Jazeera. "But so far, I've got none."
Follow Barry Malone on Twitter: @malonebarry