Just a few feet away, American soldiers stood by the side of the highway directing convoys of fuel trucks heading north. They must have noticed the cluster of men in plainclothes arming themselves with automatic weapons. They didn't acknowledge it. No one demanded to see our identification or weapons permits. No one even asked what we were doing. By local standards, what we were doing was normal. Only a moron drives to Baghdad unarmed.

There were no morons in our convoy. These were American civilian contractors, employees of one of the private security companies the U.S. government has hired to pacify and reconstruct postwar Iraq. The group was led by Kelly McCann, a 45-year-old former Marine officer, and security expert who also works as an analyst for CNN. McCann and I have been friends for a couple of years. When I asked him what exactly civilian contractors were doing in Iraq, a subject about which there has been much speculation but relatively few published facts, he offered to show me.

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I'd already gotten part of the answer earlier that morning. At 6:30 a.m., eight of us had gathered in a hotel suite outside Kuwait City for a briefing on our drive to Baghdad. Apart from me, everyone in the room was working for DynCorp International, an American firm that specializes in high-risk contract work for the Pentagon and the State Department. Pick an unsafe country and DynCorp is likely to be there. In Afghanistan, DynCorp bodyguards protect Hamid Karzai, the most imperiled president on earth. In Colombia, DynCorp pilots fly coca-killing crop dusters slow and low over drug plantations, an integral part of Washington's Plan Colombia. DynCorp is in Kosovo, Israel (three of its employees were blown up and killed in Gaza last year), East Timor, Sarajevo, Saudi Arabia, the Philippines, Liberia, and many other sketchy places. Last spring, DynCorp—along with Kroll Inc. and as many as 20 other large private security companies, and perhaps dozens of smaller ones, employing tens of thousands of individual contractors—came to Iraq.

Less than a month after U.S. troops occupied Baghdad, DynCorp won a $50 million contract from the State Department to help instruct the country's police and prison guards in the use of modern, non-torture-related law-enforcement techniques. (All told, the State Department and the Pentagon have issued contracts worth more than $2 billion for security work in Iraq.) DynCorp set about hiring close to a thousand American cops to move to Iraq and accompany their Iraqi counterparts on the job. The pay was good—up to almost $155,000 a year, most of it tax-free, plus full expenses—but Iraq is a dangerous place to live. So dangerous that DynCorp also had to hire security contractors, many of them veterans of elite special-operations units in the U.S. military, to keep the cops from getting killed once they got there.

I was going to Baghdad with the security contractors. Once we arrived, they'd spend most of their time tightening security around two hotels in the city, the Gardenia and the Baghdad, which housed the American policemen and other DynCorp employees. Both places were obvious targets for Iraqi insurgents. Both had been attacked repeatedly, the Baghdad Hotel with a devastating suicide bombing a few months before. Kelly McCann had come to check up on the work his men were doing and to bring them several cases of security and surveillance gear they couldn't get in Iraq.

At the moment, though, everyone in the room was focused on simply getting to Baghdad. Commercial flights into the city had been suspended after a series of surface-to-air-missile attacks, one of which blew a chunk of a wing off a DHL cargo plane. The overland route was now the only option. It wasn't a great option. In the previous three months, at least nine civilian contractors had been killed in the Nasiriyah area alone. Through which we'd be driving. Hence the briefing.

A former Special Forces sergeant named Jack Altizer set his laptop on a coffee table and began a PowerPoint presentation on all the things that could happen to us on the way. He spoke like a man who'd taken dangerous trips before. His language was crisp and technical, like an NTSB spokesman after an airplane crash. The primary threat, he explained, would come from improvised explosive devices hidden by the side of the road. Typically, an artillery shell, or a series of them daisy-chained together, would be buried under rocks and detonated by remote. He clicked the mouse and an image appeared on the screen showing the result. It was an aerial shot of the aftermath of a recent ambush. The vehicle, an SUV very much like ours, had been pulverized. Even from a distance, you could see that whoever had been in it must be dead.

Not that the attackers took chances. "They cleaned it up with small-arms fire," Jack said. "Cleaned it up" meant "unloaded AK-47s into the bodies."

The briefing went on like this for half an hour. It wasn't clear just who the attackers might be—carjackers, Al Qaeda, Baath Party loyalists, or some combination of the three—only that they had been hurting a lot of Western motorists in recent weeks. Lately there had been reports of attacks from snipers, rocket-propelled grenades, and fixed-place machine guns as well as car-to-car drive-by shootings, ambushes at phony government checkpoints, and hand grenades lobbed through windows in traffic.

And that was just part of what could go wrong on the highway. There was always the possibility that jumpy coalition forces might fire on us, as the 82nd Airborne had done two weeks before to a food-for-oil convoy on the road to Jordan. Small children might run out in front of our vehicle. Or we might simply have a fatal car wreck.

The last scenario didn't seem far-fetched. To make the SUVs harder to hit, we'd be traveling fast, between 110 and 120 miles per hour the whole way, including, if possible, through towns. "Pretty much for no reason will we stop," Jack said. "Drivers, if you're disabled in the kill zone, stay off the brakes. We'll ram you out of there." In other words, even if you've been blown up, be prepared to keep moving. With that, he closed his laptop and we were off.

By local standards, what we were doing was normal. Only a moron drives to Baghdad unarmed.

I was anxious about the border crossing. Before we'd left the U.S., I'd heard that some sort of visa or stamp or other official-looking document might be required to enter Iraq. I'd never managed to get one. As it turned out, no one cared. The American soldier standing at the border just nodded at the vehicles and waved us through. We rolled across doing 30.

A moment later, we made our pit stop for guns. I was busy scribbling in my notebook when one of Kelly McCann's men, a former marine sniper named Shane Schmidt, walked over with an AK-47. Do you know how this works? he asked. I nodded. The week before, Kelly had shown me the basics on his firing range. (Designed by the Soviets to be effective in the hands of teenaged peasants, the Kalashnikov is not a complicated weapon.) Schmidt handed the gun to me. "Take care of it," he said. "If we get hit, don't panic. Collect your thoughts and shoot back."

He stepped back a foot and narrowed his eyes, sizing me up to see if I was the sort of person who might start pulling the trigger indiscriminately once trouble started. "Select your fire. You've got 60 rounds of Iraqi-made ammunition. That's it. Make each one count." I said I would, then racked a cartridge into the chamber, pushed the selector to safe, and got in the car.

Under ordinary circumstances, I would have been reluctant to accept the rifle. I'm not uncomfortable around guns—I've hunted for most of my life—but bringing them on stories is considered taboo. Journalists typically don't carry weapons, even in war zones, for fear of compromising their status as neutral observers. If you're armed, the theory goes, other armed people will consider you a target. Sounds reasonable, except that in Iraq, journalists are considered targets anyway. Thirteen of them were killed there in 2003. All apparently were unarmed. Carrying a gun doesn't make you safe. But it can make you safer. That was enough for me.

Less than an hour into the drive, we got the first sign that someone was watching us. One of the Citroëns in our convoy radioed to say that a pickup truck was coming up from behind extremely fast, even faster than we were going. Jack Altizer had already picked up transmissions on his surveillance gear indicating that two people nearby were communicating on walkie-talkies. It looked like the classic setup to a carjacking: spotter by the side of the road sees Westerners in a convoy; gunmen in a chase vehicle pull up alongside and force them off the road. Or just shoot them.

I was riding in one of the SUVs, a mud-splattered Nissan, in the backseat behind Kelly and Bill Frost, another former marine. Kelly and I were talking about the approaching pickup when suddenly it appeared right next to us.

There were three young Arab men inside. They were inches away from our driver's-side window, maintaining our speed and giving us hard looks. Kelly's voice never changed its tone. He raised his MP5 off his lap, extended it across Bill's chest, and pointed the muzzle at the men in the pickup. They hit the brakes hard, disappearing into our rearview mirror. Bill never took his eyes off the road. Kelly kept up the conversation as though nothing had happened.

Just south of Nasiriyah, we stopped for gas. Despite having one of the world's largest oil reserves, Iraq has relatively few filling stations. Thanks to sabotaged oil pipelines and a huge glut of new vehicles (more than 300,000 since the war), every station has a gas line. Some are more than a mile long. People can wait for days, camped out in their cars, for a full tank. We had no intention of doing that. Waiting in line, stationary and exposed, was simply too dangerous. Instead, we commandeered the gas station.

All four vehicles roared in at high speed. Two went directly to the pumps. Two formed mobile roadblocks near the entrance. Contractors with guns jumped out and stopped traffic from coming in. Others took positions around the perimeter of the station. Kelly motioned for me to stand guard with my rifle by the back wall. There was a large and growing crowd around us. It looked hostile.

And no wonder. We'd swooped in and stolen their places in line, reminding them, as if they needed it, of the oldest rule there is: Armed people get to do exactly what they want; everyone else has to shut up and take it.

It wasn't until later after we'd left the gas station and were back on the highway, that I felt guilty about any of this. Kelly, to his credit, felt bad, too. There had been quite a few children there. I'd seen them watching as we forced their fathers out of the way to get to the pumps. "We neutered their dads," Kelly said. He was right. We had. And we'd had no choice. It was horrible if you thought about it.

I didn't have a chance to think much about it. We were doing 120 again, weaving between buses and fuel trucks as if they were traffic cones. Bill was at the wheel, chaining Wint-O-Green Life Savers and staring straight ahead. Bill was one of the largest human beings I had ever seen. A former Force Recon sergeant, he had a chest so broad, it seemed impossible. The ceramic plate on the front of his body armor looked like a postage stamp on a balloon. Kelly called him Barney Rubble. He was a remarkable driver.

Coming into a turn on the main drag through Nasiriyah, we hit an oil patch doing about 70. Suddenly we were off the road, sliding sideways. Through my window, I watched transfixed as a building approached at high speed. I could see spidery cracks in the concrete walls, tiny chinks in the wooden door frame. We are going to wind up inside it, I thought. But somehow we didn't. At the last possible second, we shot back across the pavement, onto the dirt divider. Oncoming cars swerved away. Then we came back. And forth. And then we kept going, through downtown Nasiriyah, up onto curbs, into the opposite lanes, screeching through traffic circles, blaring the horn, and barely slowing down. It was thrilling. And no doubt deeply offensive to every other living thing within a ten-mile radius. But there wasn't time to ponder that.

I spent the rest of the trip to Baghdad watching out the window for people making sudden movements. Apart from its dangers, much of Iraq isn't very interesting to look at. The landscape is flat and dun-colored. The dirt just beyond the highway is littered with hunks of twisted and mangled metal, some of it the detritus of wars, some of it just unclaimed junk. The countryside looks muddy and broken. Fires from the burnoff of distant oil refineries give the horizon a hazy, sinister look. It's not an appealing place.

Outside of the heavily fortified—and relatively safe—U.S.-controlled "Green Zone" that surrounds Saddam's former main palaces in Baghdad, you can spend days without hearing English or seeing an American flag. Almost nowhere is there the faintest whiff of American cultural influence. People light up in elevators and carry Kalashnikovs to the dinner table. Gunfire and explosions are background noise. It is a place with almost no Western-style rules. It's not a bit like Denver.

You'd think it would be. According to the Pentagon, there are more than 100,000 U.S. troops stationed in Iraq. The country seems to have swallowed them. We drove from the Kuwaiti border to downtown Baghdad and back again and didn't see one on the way—more than 700 miles on major roads without catching a glimpse of a single American in uniform.

If the goal is to control the country, there are not enough American forces in Iraq. If the goal is to rebuild it, there could never be enough. The U.S. military simply doesn't have the manpower. As it is, the Pentagon could not fight even a small war without the considerable help of civilian contractors. In Bosnia during the peacekeeping mission, there was at times one contractor for every soldier. That was nearly a decade ago. The military has grown smaller since and even more dependent on contractors. On the battlefield, contractors cook soldiers' food, deliver their mail, provide their housing, and take care of their equipment. (DynCorp maintains virtually all U.S. military aircraft in the Middle East.) In Iraq, they are sometimes nearly indistinguishable from soldiers.

Civilian contractors have been hired to destroy captured Iraqi weapons, clear unexploded ordnance from military bases, transport armored vehicles into the country, and train the new Iraqi army. This in addition to vast logistical support (providing water, power, and fuel to U.S. troops), as well as every sort of humanitarian task, down to providing pencils and rulers to Iraqi schoolchildren.

It's a fruitful arrangement for both parties. In the long term, contractors are cheaper to use than troops, at least theoretically. (Civilian contractors won't be clogging the VA system 30 years from now.) Many of them are good at what they do. And they free soldiers to do what soldiers do best. With civilians handling a portion of the logistics, the Pentagon can focus on the purely combative elements of warfighting—though as it turns out, these civilian contractors do some of that, too.

For the contractors, the allure is simple: generous pay. The work can be risky and uncomfortable, but the money is good. An experienced security consultant willing to live in unruly places can make $250,000 a year in Iraq. For a man coming from a career in the service, as almost all contractors who handle security are, this is a colossal step up. Plus, there is no one around to make you spit-shine your shoes. As Dave Smith, a former British soldier who has worked as a contractor all over the world (including, for a time, in Liberia, for the now-deposed war-criminal president Charles Taylor), put it: "The difference between a contractor and a military guy is I'm getting paid five times as much and I can tell you to get fucked if I don't want to do it." For a certain sort of person, it's a great gig.

The problem is finding that sort of person. Carrying an automatic weapon in a Third World country, beyond the easy reach of higher authority? The job description is like a bug light to borderline personalities. Big companies like DynCorp have every incentive not to hire flakes and compulsive danger seekers. The bad publicity isn't worth it. But in a situation like Iraq last year, in which the federal government threw hundreds of millions of dollars at reconstruction companies, which in turn rushed in thousands of new security contractors, the screen could not be very fine. There are civilians toting guns in Iraq who shouldn't be.

Some of them are easy to spot. I ran into one late one night outside the Gardenia Hotel, a dumpy former office building. Kelly and I were staying in a house across the street, and I'd walked over to see if I could find someone to do my laundry. Standing on the front steps was a middle-aged Englishman. He introduced himself as Richard, a former member of the 22nd SAS. He had a rifle slung over his shoulder, and he was slobbering drunk. Hearing my accent, he immediately lit into Americans as fearful and weak. "Come with me, my Yankee Doodle Dandy wanker," he said. "I'll take you places you've never been."

Like where? I said. He looked as if he were about to tell me. Then he stopped and lurched forward, almost on top of me. 'You're not Irish, are you?" he demanded, breathing in my face. Nope. "Good man!" He all but embraced me. He'd killed enough of the Irish in Ulster, he said. He'd hate to have to do it again.

About 10 days after I left Iraq, Richard put three bullets into a man he was supposed to be protecting. Apparently, it was an accident. He'd forgotten to take his rifle off automatic and ... well, you know. The man survived. Richard was fired. It turned out he had never served in the SAS.

It's hard to know how many Richards are working as contractors in Iraq. None work for Kelly McCann, which is one of the reasons DynCorp subcontracted his company to come to Baghdad, to straighten out some of the messes created by the postwar hiring spree. McCann's company, a division of Kroll that specializes in high-end security, has only 18 employees. All are extensively vetted. All, like their boss, are disciplined and superior, exactly the sort of people you'd want standing next to you if someone started shooting in your direction.

During the week that I was in Baghdad, Kelly and his men spent their time trying to secure the area around the Gardenia, an industrial neighborhood across the river from the Green Zone. In addition to being filled with Westerners, the hotel is just down the street from an Iraqi police station, a dangerous place to be. (At the time, police stations were being blown up or coming under fire daily in Baghdad.) The contractors had turned the entire street into what looked to me like a garrison.

There was a manned roadblock at one end, covered by gun positions on roofs above. The hotel garden was strung with netting to repel RPGs; its windows were covered with Mylar to reduce flying glass from bomb blasts. Teams of plainclothes security men patrolled the surrounding neighborhood at all times. Only approved delivery trucks were allowed on the street. When a building contractor wanted to deliver a load of bricks to a homeowner building an addition, guards accompanied the driver to the brickyard to make certain no explosives were added along the way. "I'm building my own Green Zone," said Chad Morman, the 29-year-old Georgian in charge of physical security around the Gardenia.

I liked Chad. Like many of the men who work for Kelly, he had a ferocious background—marine close-quarters-combat instructor and amateur kick-boxer—but a strikingly understated personal demeanor. He rarely raised his voice. He never boasted or talked about hurting people. If you run into him at Home Depot, you'd never guess what he did for a living. One night after dinner, I accompanied him as he patrolled the area around the hotel.

The first thing I noticed was how popular Chad was with animals. Every 20 yards or so, a cat seemed to run from the bushes and brush against his trousers. This struck me as unusual, mostly because you don't see many pets in Iraq. Observant Muslims don't as a rule like dogs—Muhammad specifically condemned them—and the bias apparently extends to other small, furry domesticated animals. Along with divergent beliefs about toilet paper, this is part of the great cultural divide between Iraqis and their occupiers. Sometimes it is a source of tension. "Are people who don't like dogs even worth liberating?" I heard one American contractor wonder aloud.

I mentioned this to Chad. He told me that when he first arrived in Baghdad, his guards amused themselves by torturing stray cats, kicking them, and pelting them with rocks. Chad put an end to this immediately. "I told them if they bothered the animals, I'd shoot them. I was sort of joking, but they believed me." Ever since, the guards had treated the cats like sacred objects, giving them wide berth and, when possible, shepherding them Chad's way. The cats apparently were grateful.

I told them if they bothered the animals, I'd shoot them. I was sort of joking, but they believed me.

We were almost to the end of the street when we heard voices. It sounded like young men speaking in stage whispers, and it was, three of them. They emerged from the shadows directly in front of us. "Stop!" Chad yelled, pulling a .45 out of his leg holster. One of them kept coming, walking purposefully with a cigarette in his mouth. "Stop right there!" At about 25 feet, Chad leveled the gun at the man's chest. At 15 feet, he pulled back the hammer. The man was about a foot from being killed when he finally stopped. Without lowering the gun, Chad motioned for the men to turn around. They did, and so did we. We were outnumbered and had only a handgun; there wasn't much to do but leave.

We returned to the post, and Chad told the guards what had happened. Go find out what those guys are doing there, he said. "If they live here, that's okay. If they don't, tell them to move the fuck on." The guards nodded eagerly and trotted off. "Wait!" yelled Chad. The guards stopped. "Don't shoot anybody unless somebody shoots at you." The guards nodded again. Chad turned to me. "You got to tell them that. If someone pisses them off, they're likely to open up."

The guards, like most DynCorp hires in Iraq, were Kurds from the north of the country. "They're more loyal," Chad explained. "Plus, they don't like people from Baghdad." This made them less likely to be co-opted by the locals. It also made them somewhat hotheaded.

A few minutes later, the guards returned with the three men. Chad was surprised. "There's the dude I pulled a gun on," he said. He hadn't expected to see the man and his friends again. The guards, meanwhile, were pleased with themselves. They deposited the prisoners in front of their boss with obvious pride, like a cat dropping a mouse on the kitchen floor. The three men looked confused and irritated.

Which made sense, since they lived in the neighborhood and, strictly speaking, hadn't been caught doing anything wrong. This all became clear fairly quickly. "If they live there, it's no problem," Chad said to a guard who was acting as the translator. "Tell them it's no problem. I just wanted to see what they were doing down there."

But it wasn't so simple. Apparently one of the men had an attitude problem. He'd been rude or mouthy or something less than grateful on the walk down the street. The guards were anxious to shoot him. One of them pulled Chad aside to ask permission. "No, no, no," Chad said, shaking his head. The guard looked disappointed. "Any time," he said in heavily accented English. "Any time." He meant it.

A little before midnight, I went up to the roof to call my wife from a satellite phone. About a minute into the conversation, I heard gunshots. They sounded close. I tried to ignore them. They got louder, closer. The shots were coming from two or three directions. There were several AK-47s and at least one pistol. Someone was firing very near our house.

Actually, at it. I'd heard people talk about the funny cracking noise that bullets make when they pass close over your head. It took me a moment to realize that was the sound I was hearing. I sat down. "What is that?" said my wife, who was on a tree-lined street 6,000 miles away, driving the kids home from school. "Nothing," I was about to say when the door to the roof opened and an Iraqi man with a rifle ran out toward me.

It was one of Chad's guards. He was squinting, trying to adjust his eyes to the darkness. He looked agitated. Suddenly, I could see what was about to happen. He'd spot me squatting in the shadows, panic, and shoot. I'd die on a roof in Baghdad, killed by one of the most pro-American Iraqis in the city. All while talking to my wife. It wouldn't be a noble death.

"It's me!" I yelled. "American!" The guard lowered his rifle. I got off the phone and ran downstairs to my bedroom. The hall and stairway reeked of cordite. Outside, the firing had intensified. The noise sounded different from usual. It wasn't the typical fully automatic fire, sustained and essentially uncontrolled. (Arabs have a well-deserved reputation for "spray and pray" marksmanship.) The shots were coming in short bursts. Someone was aiming. I took this as an ominous sign.

Kelly had gone to bed an hour before and was just waking up when I came in. I filled him in on the gunfight as casually as I could. He seemed interested but not worried. He became more concerned when Chad burst in. Chad was breathing hard. He had just come from outside, where several firefights were going on. "They're closing in on us," he said.

The hair on the back of my neck went up. I pictured men in checkered kaffiyehs charging up the stairs with guns, a final desperate shootout. Kelly turned to me. "Put on your vest," he said. I threw the armor plates over my head, fumbling with the Velcro straps. I grabbed my gun and went out into the hallway, trying to remember to stay away from the windows. Kelly and Bill Frost joined me, and we headed up to the roof.

By the time we got there, whoever was laying siege to our house (two different groups of men, we later learned) was being chased off by return fire. Kelly looked around for a minute, then went back to bed. Bill and I stayed up for another hour talking with Chad on the roof. Bill had spent months in Somalia around the time of the Black Hawk disaster in 1993, commanding a surveillance team in downtown Mogadishu. Feuding warlords, khat-addled lunatics driving pickups with .50-caliber machine guns mounted on the back—it sounded like a hairy place. Bill said Baghdad was more dangerous.

As he spoke, he leaned over the side of the building, scanning the street below and thinking about how he'd attack the compound if he were an Iraqi insurgent. Wouldn't be hard, he concluded. "Fifteen guys with RPGs could lay waste to this place." (The next day, Bill announced plans to put a new gun emplacement on top of the apartment building across the street. "We're going to tell the people who live there. They can eat a cold bowl of fuck if they don't like it.")

Finally, the adrenaline subsided and I headed off to sleep. As I was walking across the roof, another firefight broke out in the neighborhood, this one a few blocks away. Bill and Chad ignored it. The hallway still smelled of cordite when I got downstairs.

It wasn't until I was flat on my back that the strangest part of the night sunk in: No one outside our immediate compound had seemed to notice the firefight. The gunfire had gone on for 15 minutes. The noise had been tremendous and unmistakable. Yet nobody—not U.S. soldiers, not cops from the Iraqi police station 150 yards away, not representatives of the famously benevolent "international community," whoever they might be—had come by to ask what happened, who did it, or if anyone was hurt. There were no authorities to call. No one cared. We were totally alone.

Not as alone as the rest of the people in the neighborhood, however. We were on a residential street. Iraqi families lived on both sides of us. What did they think? Hundreds of rounds had been fired—hundreds of needle-tipped, copper-jacketed missiles whipping through the neighborhood at half a mile a second. What happened to them all? Where did the bullets go? Into parked cars and generators and water tanks. Into people's living rooms and kitchens and bedrooms, and sometimes into human flesh.

It must have been terrifying to live nearby or to live anywhere in Baghdad. You couldn't blame the coalition forces exactly. They weren't doing most of the shooting. But they didn't seem to be doing much about it, either. On the street where I was staying, they weren't doing anything. And how could they? All the foreign troops in Iraq hadn't been able to keep the country's main airport safe enough to use. A single block in Baghdad wasn't going to get their attention. By necessity, it was left to civilian contractors, or whoever else had the time, energy, and firearms to police their own tiny sections of Iraq.

The Coalition Provisional Authority that now runs Iraq has been half explicit about this. The CPA has acknowledged that civilians must carry weapons by establishing rules about what sorts of weapons they can carry (small arms only—no grenades, .50 calibers, or RPGs). It also freely issues photo-ID weapons permits. But the authority has made no provisions for legitimately purchasing guns and ammunition. A contractor working in Iraq has to have firearms, but he can't buy any from the U.S. military. Nor can he easily ship his own into the country from the United States. His only practical option is to find guns on the local black market—"Our own personal gun buyback program," as Bill put it.

One afternoon, Jack Altizer invited me to see the DynCorp armory, located in a storeroom in the basement of the Baghdad Hotel. The room, about 20 feet square, was stacked floor to ceiling with weapons. There were footlockers full of AK-47s, dozens of crates of ammunition, shelves sagging with every sort of exotic weapon: a Thompson submachine gun from the '30s, a World War II-vintage Soviet burp gun, Mausers, Walthers, guns so old and weird they were hard to identify. On a table in the middle of the room were more than a dozen 9mm pistols, each with "Gift from Saddam" stamped in Arabic on the barrel. In the corner were two leather shotgun cases. They had once held 12-gauge side-by-sides, custom-fitted in Paris. Both were monogrammed S.H. They came from one of the presidential palaces.

Where did you get all this? I asked. Jack grinned. "I got here when there was still looting. We decided to join in." In fact, he had little choice but to join in. He needed guns for his men, and there was no other way to get them. At the time, there was so much weaponry floating around Iraq, that no one knew what to do with it. At one point, a U.S. soldier offered to give Jack a million and a half AK-47 rounds. Logistics prevented him from accepting. "I couldn't carry it to my room," he said.

It's not hard to find guns in Iraq. But once a contractor gets them, he receives virtually no instructions from the U.S. government on when and how he is allowed to use them. The only firm guideline so far has come from chief administrator Paul Bremer himself. At a meeting with contractors in the Green Zone last fall, Bremer conceded that civilians in Iraq could have to protect themselves because the CPA could not guarantee anyone's safety. His one request: Identify your target before you engage—know whom you're shooting at.

This level of ambiguity makes many contractors nervous. As former soldiers, they prefer clear rules of engagement. What if they kill someone? Worse, what if they kill the wrong person? Neither would be unusual in a place like Iraq. Then what? If a U.S. soldier shoots someone under murky circumstances, the Army's Criminal Investigation Division looks into it. But the CID has no authority over civilians off base. "I don't even know that if you engage someone there's even an investigative authority to follow up," Kelly said. "With no parameters, how do I know if I've done something wrong? It's like the Wild West, but nobody's the sheriff."

Or, depending on how you look at it, everybody is. Last summer, a British contractor was run off the road by bandits on a highway south of Baghdad. The contractor, a former SAS man, got out of his car and pretended to surrender. When the bandits approached, he shot both of them. One didn't die immediately, so he clubbed him to death. The Brit was still laughing about it when Bill ran into him a week later.

Not all contractors want more CPA oversight of their activities. That's understandable. There's something to be said for limited bureaucratic interference. One night in December, two DynCorp contractors caught a man they'd been looking for outside the Baghdad Hotel. According to local witnesses, the man had kidnapped several children and attempted to sell them. The contractors reduced him to a bloody mound before turning "what was left of him" over to the Iraqi police. They told me about it at breakfast the next morning. They looked pleased.

Of course, contractors aren't always high-minded. With no one watching, it's tempting to settle scores. The week before I arrived, Sean Penn came to Iraq on some sort of special assignment for the San Francisco Chronicle. The actor was getting out of a cab in downtown Baghdad when a group of contractors spotted him. The contractors didn't share Penn's politics. Plus, they found the idea of him annoying. So they took his camera and made him stand in the rain for 45 minutes while they ran an imaginary security check on his equipment. There was nothing Penn could do about it. They had guns. He didn't. Tough luck.

Kelly told me that the maximum he allowed any of his men to stay in Iraq without a vacation was three months. Unlike the military, contractors work in relatively isolated conditions, without the security and support of hundreds of their peers. In this environment, the ambient threat—the constant, sometimes sublimated, but always present knowledge that you could get killed—can get to a person quickly. People get twitchy. I was beginning to feel it after just a week.

It started one morning while we were driving through a traffic circle downtown, on our way from the Gardenia to the Baghdad Hotel. An Iraqi man in a Crown Victoria turned his car around in the middle of the circle and came after us, trying to T-bone our SUV. Bill, who was driving, whipped onto a side street, then pulled a high-speed U-turn. The man in the Crown Vic was right behind, bearing down. There was no question now that he was trying to hit us. I was lying in the cargo area in the back of the Nissan, trying to get as flat as possible as Chad aimed his MP5 over my chest.

Suddenly Chad yelled, "Wait! There's a kid in the car." I looked up. He was right. In the passenger seat was a boy about six. The man, whoever he was, had a death grip on the wheel, obviously determined to commit some life-altering act. Bill swerved, then slammed on the brakes. The Crown Vic flew past.

I still don't know what that was all about, though there was violence in it. For some reason, more than anything, it made me want to leave Iraq.

We were planning to leave the next morning anyway. For the final 24 hours, I thought a lot about death. I'd thought about it some before leaving the United States, of course. I'd written out a will and letters to my wife and children. On the flight into Kuwait, Kelly and I talked about dying. "Everybody thinks it won't happen to them," he'd said. "But why not? It's going to happen to someone."

It had seemed like a good point then. The words penetrated deeper every day we were in Iraq. The thought was unavoidable. During the entire week, there was only a single sustained period when there wasn't gunfire and explosions in the background—when we had lunch with a Pentagon official on the fourth floor of the nearly deserted Baghdad airport. As Bill put it one morning at breakfast, grimly, "It's just a matter of time."

Where did the bullets go? Into people's living rooms and kitchens and bedrooms, and sometimes into human flesh.

We left Baghdad at 6:30 in the morning. Kelly was driving this time. He turned out to be as talented as Bill. On the highway out of the city, we squeezed between two tractor-trailers at about 95 miles an hour. I could have reached out and touched either one with only my fingers protruding from the car. It was exciting as hell. I was going to miss driving in Iraq.

I was not going to miss Nasiriyah. The city has about as bad a vibe to it as any place I've ever been. Ten miles away, my skin began to crawl. The fact that our fuel tanks were almost empty added to the tension. We were driving slowly on the outskirts of town, caught in traffic. It was market day, and the road was lined with hundreds of people, most of them staring at us. Both gas stations we passed were closed. Someone nearby started firing a gun at us. Kelly pulled the SUV into the oncoming lane, and then back again. There were too many vehicles to go anywhere. We were boxed in.

A few tense minutes later, we came to a working gas station. It was packed with people, crowds of them, some waiting for gas, some just milling around outside a mosque next door. It was the worst possible place to stop, but there was no choice. We needed fuel. We initiated the gas-station takeover.

It was different this time. I hadn't thought about it till now, but we had fewer armed men with us than we'd had driving in. Kelly stayed with the car, which was left running in case we needed to leave quickly. I hopped out with my rifle to keep an eye on two large groups of men who seemed to be approaching us. I walked about 20 feet, then turned to my left to see what the man next to me was doing. That's when I realized there was nobody next to me, no one whose lead I could follow. I was by myself.

During our first conversation about going to Iraq, Kelly and I had talked about situations like this. It's one thing to believe in the principle of self-defense. Most people do. It's quite another to make the conscious decision to kill someone. Kelly had made it clear that I'd have to decide ahead of time whether I'd be willing. "Final confirmation of an attack usually comes in the form of injury to you," he'd said. "If you feel threatened, engage, up to and including lethal force." Survival means acting first. Hesitation equals death.

I'd had plenty of opportunities to mull this over since getting to Baghdad. I didn't want to hurt another person. The idea sickened me. But now I knew for certain that I would, without hesitation.

The groups of men were definitely walking toward me now, talking to one another and looking angry. The crowd behind them was getting larger and more agitated. In my peripheral vision, I could see shapes, people darting in and out between cars parked in the gas line. I hoped someone else was watching them.

At the center of the group advancing on me were two youngish men with tough-guy expressions on their faces. They were obviously leading whatever was about to happen. I decided to shoot them first. I'd start with the one on the right. I unfolded the AK's paratrooper stock and tucked it into my shoulder, raising the muzzle. Then I switched off the safety. I waited for one of them to make a quick movement.

Neither one did. In fact, both stopped where they were and glared at me. I glared back. Five minutes later, our tanks were full and we left.

There was no firefight at the gas station, but I left feeling as if something important and horrible had just happened. I'd been forced to make a decision about life and death. There were no official guidelines. There was no one around to make the call but me, just as there would have been no one around to judge the consequences. I could have done anything. The only rules were those I imposed on myself. I hated it. It was an instructive experience. For a moment, I felt what it is to be an American civilian contractor in Iraq.

STORY BY: TUCKER CARLSON

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