WASHINGTON - Every day, as many as 260 trucks filled with supplies for U.S. troops - from muffins to fuel to armoured tanks - are driven from the Pakistani port of Karachi across the Khyber pass into Afghanistan.

A convoy of trucks en route to Kabul passes through the village of Sayed Abad in Afghanistan. (Joel Saget / AFP-Getty Images) Supply lines through the high mountain passes of Afghanistan have always been a dangerous mission - the Soviets reportedly spent most of their occupation in the 1980s fighting off attacks. The U.S. has chosen another method - outsourcing the delivery and even the protection of the vehicles to private contractors.

Almost four out of every five containers delivered to Afghanistan are now hauled by a consortium of eight Afghan, Middle Eastern and U.S. companies under a 2.16-billion- dollar contract called Host Nation Trucking (HNT) that started May 1, 2009. A typical large convoy of trucks may travel with 400 to 500 guards in dozens of trucks armed with heavy machine guns and rocket-propelled grenades.

These trucks come under irregular attack. On Dec. 7, 2008, a parked convoy of trucks carrying military vehicles for U.S forces in Afghanistan near Peshawar was attacked by insurgents who torched and destroyed 96 trucks. As recently as Jun. 8, 2010, a convoy of contractor was attacked when it stopped at a depot just outside of Islamabad. The insurgents burnt 30 trucks and killed six people.

In November 2009, Aram Roston of the Nation magazine published a startling article: The trucking and security contractors were paying off warlords, and perhaps even the Taliban.

On Tuesday, a new report by U.S. Congressional investigators titled: "Warlord, Inc. Extortion and Corruption Along the U.S. Supply Chain in Afghanistan" confirmed Roston's allegations. The six-month investigation was conducted by the staff of the House Subcommittee on National Security and Foreign Affairs, which is chaired by John Tierney, a Democrat from Massachusetts.

"The HNT contractors and their trucking subcontractors in Afghanistan pay tens of millions of dollars annually to local warlords across Afghanistan in exchange for 'protection' for HNT supply convoys to support U.S. troops," wrote the investigators in the 79-page report.

"Within the HNT contractor community, many believe that the highway warlords who provide security in turn make protection payments to insurgents to coordinate safe passage."

Memos show that occasionally the contractors even worked with the insurgents to shake down the U.S. military for more money.

"U.S. taxpayer dollars are feeding a protection racket in Afghanistan that would make Tony Soprano proud," Tierney said in a prepared statement, making reference to the fictional mafia boss of a popular TV series. "This arrangement has fueled a vast protection racket run by shadowy network of warlords, strongmen, commanders, corrupt Afghan officials, and perhaps others."

The report comes on the heels of a two-day hearing in the U.S. Congress by the Commission on Wartime Contracting into abuses - including multiple charges of killings of civilians - by private security contractors hired by the State Department and the Pentagon in Iraq.

Three high-ranking military officials were asked to report to Tierney and other members of the subcommittee at a public hearing in Congress on Tuesday. "Why weren't questions raised about these allegations earlier?" asked Congressman Mike Quigley, a Democrat from Illinois, echoing similar questions asked repeatedly by Tierney.

"I was personally unaware of these kinds of allegations but we take it seriously," said Lieutenant General William Phillips, principal military deputy to the assistant secretary of the army for acquisition, logistics, and technology. He explained that it was difficult to investigate corruption in Afghanistan.

Tierney dismissed this answer. Noting that the allegations were widely rumoured within days of the new contract and appeared in the media in late 2009, he pointed out that his staff was easily able to secure meetings with one of the warlords. "It took one email and when we met with him, he readily admitted to bribery and corruption."

Perhaps a more accurate answer came from Brigadier General John Nicholson, the director of the Pakistan/Afghanistan Coordination Cell for the Joint Chiefs of Staff at the Pentagon. The issue that his office ranked highest, said Nicholson: "Was the product delivered on time?" explaining that the military's highest priority was making sure that supplies got to the troops.

Congressman Jeff Flake, a Republican from Arizona, said that a more appropriate question was: "Where is the tipping point when we say that that the funding of a parallel authority structure should become unacceptable?"

"There seems to be very little indication the Department of Defence is doing anything," Flake concluded.

Several experts also testified to the subcommittee that the new report presented a major problem for U.S. military objectives in Afghanistan.

Colonel T.X. Hammes, senior research fellow at the National Defence University, said that the military needed to look into whether or not the choice of contractors "directly undercut(s) a central theme of our own counterinsurgency doctrine.'

*This article was produced in partnership with CorpWatch - www.corpwatch.org.