NY Times: (reg. req'd)

Suddenly, on that May day in 2005, the copter dropped CS gas, a riot-control substance the American military in Iraq can use only under the strictest conditions and with the approval of top military commanders. An armored vehicle on the ground also released the gas, temporarily blinding drivers, passers-by and at least 10 American soldiers operating the checkpoint.

"This was decidedly uncool and very, very dangerous," Capt. Kincy Clark of the Army, the senior officer at the scene, wrote later that day. "It's not a good thing to cause soldiers who are standing guard against car bombs, snipers and suicide bombers to cover their faces, choke, cough and otherwise degrade our awareness."

Both the helicopter and the vehicle involved in the incident at the Assassins' Gate checkpoint were not from the United States military, but were part of a convoy operated by Blackwater Worldwide, the private security contractor that is under scrutiny for its role in a series of violent episodes in Iraq, including a September shooting in downtown Baghdad that left 17 Iraqis dead.

None of the American soldiers exposed to the chemical, which is similar to tear gas, required medical attention, and it is not clear if any Iraqis did. Still, the previously undisclosed incident has raised significant new questions about the role of private security contractors in Iraq, and whether they operate under the same rules of engagement and international treaty obligations that the American military observes.

"You run into this issue time and again with Blackwater, where the rules that apply to the U.S. military don't seem to apply to Blackwater," said Scott L. Silliman, the executive director of the Center on Law, Ethics and National Security at the Duke University School of Law.

Officers and noncommissioned officers from the Third Infantry Division who were involved in the episode said there were no signs of violence at the checkpoint. Instead, they said, the Blackwater convoy appeared to be stuck in traffic and may have been trying to use the riot-control agent as a way to clear a path.

You know, I get frustrated in rush hour traffic too, but that's ridiculous. I have to agree with Markos:

The use of these mercenaries has been glorified by the Right for years. But at the end of the day, their actions have hampered and perhaps even sabotaged our mission while endangering our troops.