Blackwater. The name says it all, conjuring images of imminent danger, hidden predators and night terror. From the moment Blackwater USA arrived in Iraq to protect L. Paul Bremer III’s Coalition Provisional Authority until last week, when its guards killed 11 Iraqis and wounded 13 more while escorting a diplomatic convoy through Baghdad, the North Carolina-based private security company has been known for its swaggering image and “Dirty Harry” demeanor.

All the U.S. private security armies in Iraq may be cut from the same khaki cloth, but each has its own personality. When I arrived in the country in September 2004 as a senior information officer for the U.S. Agency for International Development, bodyguards with Kroll Inc., whose credo is “in risk there is opportunity,” met me at the airport. They were British and Irish veterans of Belfast’s “Troubles” and viewed terrorists with a world-weary stoicism.

Our convoy had pulled onto the airport highway and was heading for the Green Zone when three black Chevy Suburbans flashed past. The rear door of the trailing vehicle was open, and inside sat a man dressed in black cradling a large-caliber machine gun. Bandoleers crisscrossed his chest, several handguns and a large knife dangled from his weapons harness and an enormous handlebar mustache covered most of his face.

The look was designed to inspire dread, but it was carried to such cartoonish extremes that the man resembled Yosemite Sam more than the Terminator. “That’s Blackwater,” said the Kroll driver disdainfully. “You’ll see a lot of them while you’re here.”

Once inside the Green Zone, it became clear to me that protecting American civilians was a prime directive of the U.S. occupation. A cold calculus had determined that the volunteer army could tolerate casualties but that Congress would never accept images of American civilians beheaded on Arab TV. The responsibility for protecting embassy personnel and nongovernmental contractors fell to the State Department’s Bureau of Diplomatic Security, which had regional security officers embedded in every government agency.

In post-conflict situations, these security officers normally work with U.S. Embassy Marine guards and local police. But when I was in Iraq, the police barely existed and U.S. military units were stretched to the breaking point. Indeed, around the time of President Bush’s “mission accomplished” speech on the deck of the aircraft carrier Abraham Lincoln, a Rand Corp. study concluded that, based on the postwar history of Germany and Japan, Washington would need a minimum of 500,000 troops to rebuild Iraq. Unfortunately, coalition forces numbered only 211,000. Because the Pentagon refused to increase troop levels, the State Department was forced to sign contracts with dozens of private security firms.

The companies with government contracts in Iraq have no trouble recruiting people with military or law enforcement experience. Most of the 20,000 guards thought to be working in Iraq come from the rural U.S., where a deputy sheriff is lucky to earn $40,000 a year. In Iraq, where Western bodyguards can earn $2,000 to $4,000 a week working for one of the 37 private security companies registered with the Iraq Ministry of Interior, a job with Blackwater -- which pays bodyguards assigned to the U.S. ambassador $1,000 a day -- is seen as the windfall of a lifetime.

Bodyguards protecting U.S. civilian contractors have one main goal: bring ‘em back alive. Innocent Iraqis who get in their way do so at their peril.

In 2005, when Kroll lost the USAID security contract to DynCorp International, a Virginia-based military contractor with $2.3 billion in annual revenues, the tactics of protection outside the Green Zone became more like military maneuvers. During a March visit to the Baghdad South Power Plant, our three-car convoy was joined by an OH-6A “Little Bird” helicopter that swooped low over the vehicles whenever we neared an intersection. To avoid congestion, we bounced over traffic medians, ran through a police checkpoint and used an offramp to enter the Doura Expressway, which rings eastern and southern Baghdad. As we sped down the wrong side of the freeway, a DynCorp guard tethered to the helicopter warned approaching traffic to get out of the way by throwing plastic water bottles at cars.

The return trip was much the same, save for the Iraqi one of our cars clipped when he walked into the road from between two parked cars.

Back inside the Green Zone, I told several colleagues about not stopping after hitting a pedestrian and then asked if I should report DynCorp’s behavior to the U.S. Embassy. “You got back safely, didn’t you?” came the response. “So what’s your problem?”

Because bodyguard services got paid whether they left the Green Zone or not, they made it as difficult as possible to leave.

No U.S. Embassy employee could go into Baghdad without specific map coordinates for the destination, but obtaining this information was problematic because the embassy and the military telephone networks were incompatible, and cellphones and e-mails were considered insecure. It was much easier to get an Army helicopter for trips outside the capital.

The real victim of the “safety at any cost” policy was the U.S. development program. Government careers and inflated contractor salaries depended on keeping civilians out of harm’s way. As a result, bodyguards looking out for civilians halted work at the slightest hint of trouble. In theory, billions of dollars were being spent every month on new roads, sewers, hospitals and schools, but much of the work went unsupervised during election campaigns, holidays -- both U.S. and Iraqi -- and whenever the threat level increased. One director of the USAID’s Office of Transition Initiatives signed millions of dollars’ worth of grants over the course of her year in Baghdad yet left the Green Zone only once to inspect completed work.

Still, that may have been the wisest course of action because riding with private security contractors is no way to win Iraqi hearts and minds.

Blackwater claimed last week that its employees were responding to hostile fire, and a fuller investigation of the tragedy may partly exonerate those involved. But anger over last week’s deaths will probably linger because many Iraqis remember that in May 2004, two Blackwater guards shot a Baghdad taxi driver and killed his 19-year-old passenger without warning.

In 2003, private security guards were regarded as efficient, cost-effective labor. But the unintended consequences of that assumption are piling up fast. Even if the Iraqi government does not expel Blackwater, the security firm should prepare to leave. In Iraq, the day of the gunslinger should end.

David DeVoss, editor of East-West News Service, spent six months in Iraq with the U.S. Agency for International Development.