Sgt. Alex Herron from the 3-7 Infantry Battalion, 4th Brigade, 3rd Infantry Division, occupies a police checkpoint during a patrol to secure Highway 1 as a NATO convoy passes

Light, pale dust trail several U.S. soldiers as they head past twisted and blackened tanker trucks on Highway 1 in search of the insurgents who set them on fire.

Coming upon a stand of thin trees in the village of Haft Asyab, the soldiers ask the Afghan police officers with them to search it. An Afghan commander sitting along the road says there is no need, his men have already done so.

First Platoon leader Lt. Frank Piasta stands over him. "Tell him I watched him. They didn't search these trees," he says to his interpreter.

But the Afghan commander doesn't budge. The Americans search the area themselves. Hidden in the grass they find two rocket-propelled grenades.

Highway 1 is more than just a dusty asphalt road. It is a lifeline for families, troops and businesses that connects strategic Wardak province to the Afghan capital of Kabul.

It is supposed to be an example of the success of the 12-year effort by multinational forces to end Taliban control and showcase the ability of the Afghans to handle their own security. But insurgent attacks are regular occurrences, and there is a question whether it can ever be ready for a withdrawal of U.S. troops ordered by President Obama to be completed by the end of 2014.

"Highway 1 is still the issue," says Col. Kimo Gallahue, commander of the Army's 4th Brigade of the 3rd Infantry Division.

A recent epidemic of Taliban attacks on NATO fuel convoys along Highway 1 has slowed the pace of the U.S. withdrawal from Wardak and acts as a constant reminder to Afghan and U.S. forces that the Taliban has not been defeated.

The U.S. special representative for Afghanistan and Pakistan, James Dobbins, said Thursday that Afghan President Hamid Karzai has tentatively endorsed a deal to allow some U.S. troops to remain after 2014 for added security but has yet to sign it. The deal was approved by a council of tribal elders known as the Loya Jirga.

"On the security agreement we really did not make any progress. It was a restatement of the known positions. I explained why we thought it was important to remove the anxiety and uncertainty around this as quickly as possible," Dobbins told the Associated Press.

Meanwhile, having closed some bases in preparation for a pullout, the U.S. military has been forced to send more troops to Highway 1 to combat a resurgence of violence.

Wardak was a centerpiece of the U.S. troops surge ordered into the country by Obama in 2009. It was the first province to receive surge troops, and Gallahue was one of the first surge commanders to lead a battalion to retake the province from Taliban control.

Now, Gallahue has returned here as commander of the 4th Brigade to maintain security on Highway 1 and oversee the drawdown of forces. It has not been uneventful.

Every few days, convoys of fuel tankers and supply trucks head along Highway 1 to bring fuel and supplies from Bagram Airfield outside Kabul south to Kandahar province.

A semi-official militia called the Afghan Public Protection Force maintains security for the convoys. But the militia can't, or won't, confront attackers who regularly target the trucks as they pass through the villages of Salaar and Haft Asyab.

Both areas are under the protection of Afghan police, soldiers and Gallahue's troops. The insurgents divert the trucks, steal their fuel and set them ablaze. Columns of smoke visible for miles are a usual sight, done to signal to residents that the Afghan National Security Forces cannot protect them.

"There is benefit to them from trucks burning on Highway 1," says Gallahue. "It is a symbol of insecurity."

As the summer fighting season began, the Taliban came out hard on Highway 1. Surprised by the attacks, the U.S. military moved an additional company of soldiers into southern Sayedabad district. Packed with troops, Combat Outpost Soltan Kheyl soon looked more like a base at the height of the surge rather than a drawdown.

Through the summer at least 10 Afghans and seven U.S. soldiers have been killed here, according to U.S. military forces.

Mindful of the subordinate role U.S. troops have been given recently, Gallahue's officers have spent much time advising the local Afghan army battalion. Effectiveness against insurgents is a concern, the military says.

Maj. Rob Howard arrived in May to help turn things around with a new Afghan battalion leader, Col. Mulinkadin, who he saw as effective and aggressive. Under Mulinkadin (many Afghans go by one name), the Afghan army spread into the villages. Highway attacks went down. Mulinkadin's Afghan superiors relieved him of duty, and things got worse again.

"I was angry because there's been a lot of good work out here," Howard says. "The week after Mulinkadin left, we had back-to-back convoys, both of them hit pretty hard, combined total of 44 trucks burned, in about 10 days."

Howard suspects there's some collusion between the Taliban and members of the Afghan police force posted in the region, given the attacks are so close to the police bases.

"Now do I know for a fact? Not really," he says. "But if it's time and time and time again there's either incompetency or there's collusion."

It's not just Taliban marauding over the highway. The black market trade in stolen fuel is an inducement to thieves as well. Howard also suspects that some of the tanker thefts involve corrupt Afghan forces.

"Our priorities are different from those leaders whose number one focus is, 'How do I make money today?'" he said. "But at the end of the day, the thing that's really going to make this place successful is good, honest leaders, who care more about the people they are leading than themselves."

Rohsanak Wardak agrees.

Wardak is a former member of parliament representing Sayedabad and one of Afghanistan's rare female physicians. As the head of a small clinic in the district, she treats civilian victims caught in the crossfire and says she sees corruption as well.

"I was going to my house from Kabul and there was a tanker," she says. "Two policemen went to the other side of the road, and they fired on the tanker — I saw them. The oil was coming out like from a tap, and he tells the people that the Taliban fired on the tanker. Then the people came with their big plastic barrels, and they bought the oil from the police."

Wardak says Afghan forces need to patrol more actively and fight more responsibly.

"They don't protect the road, they don't protect the villages, the civilians," she adds.

One hot afternoon, a pickup truck at the head of a convoy speeds down the road. Standing in back, wrapped in a scarf, is a gunner for the Afghan Public Protection Force militia.

A prime target for attack, the tankers in the convoy pass by the soldiers of First Platoon at the checkpoint in Haft Asyab. Another platoon waits farther down the road. Afghan soldiers are positioned in the villages and flying overhead are two A-10 fighter jets, which can pass low and strafe vehicles and buildings with automatic cannon fire. This time the jets fire flares to intimidate would-be attackers.

The sweating soldiers keep sniper rifles trained on the green zone across the highway, waiting and watching. The trucks arrive slowly at first, some painted with Pashto poetry in feathery white script, then come in a flood, hundreds in all. They make it through without incident.

Capt. Padshah, a 32-year police veteran and the commander of the Afghan National Civil Order Police in Haft Asyab, isn't optimistic about the future here when Afghans are slated to take over security from the Americans.

"We think it's going to get worse," he says. "There's going be more firefights, there's gonna be more enemy, we are gonna lose a lot of people."