Downtime is scarce during the two-month academy. Classes are held six or seven days a week.

Suicide bombers, surveillance detection and IEDs are on the agenda. The men need to be experts with a map and compass, know the fastest way to wrestle a car out of a ditch, understand which part of a vehicle blocks bullets best.

The day starts at 6:30 a.m. with a 3- to 7-mile run. Trainees set the distance and pace. There is no reveille and no red-faced drill sergeant. Even Ilic peppers his orders with "Hey dude, you know I love ya."

Says Go: "This is not boot camp. If we have to yell at them, they don't belong here."

When push-ups are demanded for mistakes, restitution is delivered quietly on the sidelines, with no oversight.

"They know they owe it," Go says. "They're trusted to do the right thing."

To graduate, students must have a near-perfect score on the gun range - twice. They have to perform well in numerous high-stress scenarios and pass three benchmark physical tests that get ever tougher. By the end, among other requirements, they get two minutes to crank out 75 push-ups and another two for the same number of sit-ups.

They also grade each other - three appraisals over two months spent eating, sleeping and learning together.

"A guy can do really well on the other things," Go says, "but it's no good if everybody hates him. We're not looking for loners."

Audio slide show: The sound of freedom at Blackwater Timeline: Private warriors through the ages What contractors give up: No health care, no retirement plan Full special report FROM MILITARY RANKS Of the 19 men listed on Blackwater’s leadership team: 6 were SEALs 4 were CIA 2 were Army Special Ops 2 were Marines 2 were Navy 1 was Army 1 was Coast Guard 1 was Air Force

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Those who fail to finish get a discount on the $20,000 tuition - a tab most trainees cover by signing promissory notes to Blackwater. For graduates, payback is deducted from future earnings. For the first two years, they are forbidden to work for Blackwater competitors.

First posts with the company are usually "static," as they say in the industry - relatively safe jobs on the lower end of the pay scale, like guard duty at a gate somewhere overseas. Those who do well will be in line for the more dangerous, more lucrative assignments.

The trainees accept that they have chosen a profession that offers no health insurance, no paid vacations and plenty of chances to die. Billiott figures it's too late to look back now anyway.

"I sold my truck and put everything in storage," he says. "If I don't make it here, I'm screwed."

Private soldiering is an ancient occupation, but the modern version is so new that the rules - and the labels - are still being sorted out.

Outsiders often refer to contractors as "mercenaries," a name that raises hackles among insiders, who say they don't fit such a cold-blooded definition.

"We prefer 'security professionals,'" said Chris Taylor, Blackwater's vice president for strategic initiatives.

Indeed, for the most part, contractors play defense - providing security for diplomats, escorting shipments, guarding gates. But the lines can shift fast in a war zone, thrusting contractors into a pivotal role, where they can influence the outcome of combat, or even instigate it. Rules and accountability become cloudy.

Contractors and soldiers also can get in each other's way. There have been episodes of friendly fire and missions that don't mesh.

Another point of tension: The military talent drain. Hefty paychecks available at companies like Blackwater are luring some of the best and brightest away from the service while creating friction with those still in uniform.

Issues like these have prompted a number of politicians to push for greater regulation of the private military industry. They want established standards and better oversight.

The spotlight fell on Blackwater in March, when Vice Chairman Cofer Black announced at a conference in Jordan that his company was ready to provide peacekeeping brigades to foreign governments and international bodies. News accounts of his speech raised the specter of a private army for rent to the highest bidder. The company insists Black never said any such thing.

It was hardly Blackwater's first time on the front page. Its contractors have shown up repeatedly in war zone photographs - a muscular wall of men in mirrored sunglasses, bristling with firepower, guarding VIPs. Those images helped make Blackwater an icon for its industry.

Then there was Fallujah, which put the company's name on everyone's TV screen - and changed the course of the war. After four Blackwater contractors were killed there, Marines were ordered to pound the city - a shift in strategy that fanned the flames of insurgency across Iraq.

Last fall, Blackwater boots turned up on American soil, some of the first on the ground after Hurricane Katrina hammered the Gulf Coast. Heads swiveled at the sight of heavily armed civilian soldiers dressed in black, but the company's quick response - and foot-dragging by government officials - led to millions of dollars worth of work in the area.

With each move, and each headline, Blackwater intensifies the debate about the role of private soldiers in today's world:

Is it truly cheaper to farm out so much of the war? Is it right to give civilian soldiers a license to use armed force? Who do they answer to if they fall short, or go too far? Is there a risk of private armies turning rogue?

Just 10 years ago, those questions didn't exist.

Neither did Blackwater.

Staff writer Jeff Hampton contributed to this report.