As the United States prepares to escalate its troop commitment in Afghanistan, the frequently counterproductive role played by private security contractors in that combat is drawing fresh scrutiny.

The Army Times reported on Tuesday that "ill-disciplined private security guards escorting supply convoys to coalition bases are wreaking havoc as they pass through western Kandahar province ... and undermining coalition efforts to bring a greater sense of security to the Afghan people, particularly because the locals associate the contractors with the coalition."

According to one Afghan security official, private security guards have killed or wounded more than thirty civilians over the past four years in just the Marwand district, and the district chief there claims that "most of them are addicted to heroin."

"Although the convoys sometimes carry U.S. military vehicles and represent a vital lifeline for the coalition effort," the Times explains, "no Afghan, U.S. or other coalition military forces accompany them. Instead, each convoy is protected by Afghan security guards armed with AK-series assault rifles and rocket-propelled grenades in sport utility vehicles."

The problem is not new. A Congressional Research Service report (pdf) obtained last summer by Secrecy Times revealed that as of March 2009 there were more private contractors working in Afghanistan for the Department of Defense than there were US military personnel. The report further warned that "abuses and crimes committed by armed private security contractors and interrogators against local nationals may have undermined U.S. efforts in Iraq and Afghanistan."

According to that report, only about 15% of the private contractors in Afghanistan are US citizens, many of them from firms like Blackwater, while more than three-quarters are Afghan nationals. The Afghans provide non-security services in areas such as construction and transportation, but they also include the "out-of-control security contractors" described by the Army Times.

Capt. Casey Thoreen, the commander of a US infantry company in the area, complained to the Times that the guards are "gun-toting mercenaries with probably not a whole lot of training. ... They’re just light on the trigger finger."

US commanders appear to be in the dark on what companies the guards are working for, how much they are being paid, or even whether anyone is vetting them. As complaints increase, however, the US military is attempting to crack down on the worst offenders.

Meanwhile, the use of local contractors appears likely to grow along with US troop levels. A senior advisor with the Center for Strategic and International Studies told Talking Points Memo this week that "there will definitely be an increase in the number of contractors."

TPM notes that "various government entities either don't know, or don't agree on, just how many contractors are currently in Afghanistan," so it's unclear whether the White House estimate of $1 million a year for each additional US soldier takes account of private contractors or not.

"After being bounced around to several DOD offices in the United States and Afghanistan that professed ignorance about the number of contractors," TPM concluded, "a U.S. Central Command spokesman told TPM today the issue would take some time to look into, and he would get back to us."