The Obama administration needs to crack down on private contractors working with our military.

The recent revelations of lewd “Animal House” behavior by private guards working for the U.S. Embassy in Afghanistan were shocking.

Employees of ArmorGroup North America, one of several private defense contractors employed by the U.S. government in Iraq and Afghanistan, created what has been described as a “Lord of the Flies” environment in the U.S. Embassy in Kabul. They engaged in hazing and sexual antics, as well as drawing in local Afghans into activities that are anathema to observant Muslims.

But the misadventures of ArmorGroup didn’t happen in a vacuum. The infamous contractor Blackwater USA (now known as Xe Services LLC) was responsible for a September 2007 shooting in Baghdad during which 17 civilians were killed. Five Blackwater guards were indicted for those shootings, and a sixth pleaded guilty.

Last month, Erik Prince, the founder of Blackwater USA, was accused in a lawsuit against his company of smuggling unauthorized weapons to his employees in Iraq, encouraging the elimination of Muslims, and trying to silence, through the use or threat of violence, witnesses in the criminal probe.

Blackwater’s legal representatives denied these allegations and added that the lawsuit should be dismissed, claiming that although the deaths of Iraqi civilians were tragic, the Blackwater guards were closely supervised by U.S. government officials.

But as Rep. Jan Schakowsky, D-Ill., said in response to the extension of Blackwater’s contract, “Every day that Blackwater operates in Iraq as a contractor for the United States, our military and diplomatic objectives are put at serious risk.’’

Beginning with the Bush administration, private contractors have assumed a growing role in U.S. military efforts in the Middle East. According to an August report issued by the Congressional Research Service, private contractors now outnumber uniformed personnel in Iraq and Afghanistan by 200,000 to 194,000. In Afghanistan alone, private contractors account for 57 percent of total personnel.

The negative fallout from the use of these contractors is not limited to outrageous behavior. Last month, it was revealed that Blackwater has been used to assemble and load missiles on remotely piloted drones used to assassinate Al Qaeda operatives in Afghanistan. While many of these missions have been successful, they often involve the accidental killing of civilians, undermining U.S. goals there.

Finally, the growing presence of private contractors, who are paid on a much higher scale than conventional uniformed personnel, has the effect of lowering the morale of those who are making the biggest sacrifice of their lives for their country.

Evidently discarding this mounting evidence, in recent months the Obama administration has chosen to extend Blackwater’s contract in Iraq, despite the fact that it doesn’t have a license to operate in that country. The fate of ArmorGroup, which had been singled out by a Senate panel for criticism months before the latest scandal, is still not determined.

When private defense contractors engaged in the Middle East’s most crucial and sensitive flashpoints behave badly, they not only tarnish the moral stature of the United States, they endanger our national security.

Ed Morales is a contributor to the New York Times and Newsday and is the author of “Living in Spanglish.” He can be reached at pmproj [at] progressive [dot] org.