Very few people outside the contracting industry really understood just what a private security contractor did before March 31, 2004. That was the day four American security contractors accompanying a shipment of kitchen equipment through Iraq were ambushed, killed, set on fire, dragged through the streets, and hung from a bridge before a cheering crowd in the city of Fallujah.

As shock subsided, questions arose. Who were these American men? If they weren't members of the military, what were they doing in one of the most volatile regions of Iraq?

All four men were private security contractors working for a company called Blackwater. At the time the company, like many others, was just getting on its feet as U.S. demand for security services skyrocketed. The government needed armed, well-trained security personnel in hostile territories. The new push started when the United States went to war in a CIA-led operation in Afghanistan in 2001. e CIA's early advance teams were not fully prepared for the pace of their own success. They quickly needed makeshift facilities to hold hostile enemy combatants and establish secure operating bases. The military wasn't yet in a position to help, so the CIA hired Blackwater.

It was a similar story when the U.S. invaded Iraq in 2003. A heavy presence of diplomats and reconstruction experts working in a hostile area meant they needed to be protected. Blackwater won a part of the contract to provide security services in the country. But being a private security contractor was a shady business, if not in the "legal" sense, in the "keeping off the radar" sense. Many of the contracts that were granted to companies such as Blackwater included clauses that severely limited the companies' ability to talk to members of the media. Contracting was, by the design of the U.S. government, secretive.

It was also designed to be nothing more than a cost-saving, stopgap measure. But as U.S. troops leave Iraq, there is an army of contractors staying behind, and 5,000 of them will be providing security services.

A contractor's experiences often don't draw a great deal of attention, unless someone is kidnapped, or has done something wrong. As Congress began to investigate the government's use of contractors several years ago, the issues that drew the most attention were the lack of clear rules governing contractors, and just how much money they were being paid. While it's true that money has always been a big draw, there are other parts of the job and lifestyle that rarely get reported.

"I remember when I got out of the military and took my first job with Blackwater," says Lloyd, "I thought I was going to be a millionaire, but after working five years in contracting, I can tell you I was chasing a carrot the whole time."

At the height of the boom in the years following the start of the Iraq war, private security contractors with military or law enforcement experience could make upwards of $750 a day. They would work for several months at a time and then come home before heading off on the next assignment. Many of the jobs didn't come with life insurance policies or medical coverage for their families back home.

"Layoffs and breaks between deployments have all affected my financial progress," says Lloyd. "It's two steps forward and one step back." He has a wife back home who is awaiting the birth of the couple's first child and says he worries because he has no pension. He reports that he has $30,000 in a 401(k) and another $15,000 in A Roth IRA. It's nowhere near the million he thought he would earn.

Another contractor, who worked for two of the larger private security companies before finding an office job back home, says it was a sense of duty after 9/11 that prompted him to leave his job as a SWAT team officer and go overseas. But the money wasn't bad, either.

"I got in so early that when I got into it the money was good," says Carter, who doesn't want to use his real name out of fear that he will have trouble getting hired for another contract if anyone knows he's spoken with CNN. "We were making $700 – $750 a day regardless of the contract. Some paid higher, some paid lower, but over time the company started paying less. They diluted the pool of skills. They lowered the qualifications 'cause they needed people. Six hundred dollars a day - pay dramatically dropped, then new companies came in - $500 day and it went from there."

Was it worth the money? "I had spent five months not eating, not sleeping, because you'd have death missions, seeing people get blown up all around me, going on dangerous missions where I could have died," says Carter. "I had so many close calls when we should have been killed, dozens of times. Small arms fire, some RPGs (rocket-propelled grenades), some grenade attacks on the vehicles. It didn't happen daily, but it was dangerous."

"I have even had people tell me that I'm not like they are because I'm a contractor," said Lloyd. "As if a rocket attack isn't just as stressful for me as it is for them, because I make "so much money.'" As if (post-traumatic stress disorder) is only for soldiers and combat veterans, because I make so much money that I have nothing to be stressed about."

Like many private security contractors working in Iraq and Afghanistan, Carter moved between contracts, sometimes working on CIA tasks and sometimes on DEA contracts. For a while, he provided base security at one of the most sensitive CIA bases in the region. On other contracts, he often had to accompany reconstruction officials to meetings with Iraqi counterparts.

Carter recalls one night where he believed that there was a good chance that he wouldn't go home to his wife again.

"Here I am sweating bullets because I know the next day I have to take someone to a dangerous neighborhood, and it's me and another guy protecting someone and I'm scared to death."

"I had no benefits, no veterans services, no college fund, no disability insurance. There were some limited benefits from the company, but we got no veteran's credit. That was a big downside. We were getting murdered on medical insurance. Couldn't get any life insurance back then," recalls Carter.

There were contractors in the early days who saved up money, put their kids through college, or paid off the mortgage, and came home. It wasn't the kind of job that many people took on thinking they could do it for 10 years. But there was another big drawback once they were home: finding a job to match their skill set wasn't easy.

"I didn't bring home one skill I could use," says Carter, who has been home for three years now but is thinking seriously about going back.

"I still stay in touch with all of my friends who are deployed. Every day they are a part of something that matters. Every day, I sit behind a desk and do nothing. I used to be working along the border between Pakistan and Afghanistan doing operations that the military wouldn't do - and now I come home and I have to answer to some boob about what I'm doing. It's such an emotional and mental letdown. I'm literally rotting," says Carter.

But if he went back now, depending on where he went, there could be even more dangers. The U.S. is still negotiating with the Iraqi government about whether U.S. contractors will be granted any diplomatic protections under Iraqi law. It's been a point of contention since Blackwater guards shot and killed 17 Iraqis in a Baghdad traffic circle in 2007. Given the unwelcoming position of the Iraqi government toward U.S. contractors in light of that shooting, it's another risk worth weighing before packing the duffel bag.

By: Suzanne Kelly / CNN.com

Experts said the two had come to this agreement in order to ease pressure on al-Kadhimi's government. It was being targeted by Iran-backed militias known as the Popular Mobilization Forces (PMF) in Iraq, who are opposed to any US presence in the country at all. The same groups are suspected of being behind ongoing drone and rocket attacks on US logistics convoys and bases as well as an assassination attempt on al-Kadhimi himself.

The plan to change the status of US troops was completed ahead of schedule. On December 9, Iraq's national security adviser Qasim al-Araji announced that the transition to a mission to "advise, assist and enable" was now complete.

Most of the US troops in Iraq are there as part of the International Coalition for Operation Inherent Resolve, whose aim is to fight the extremist group known as the "Islamic State" (IS).

Not like Afghanistan

Despite the fanfare with which they were announced, the changes are not huge in a physical sense and are certainly far from the wholesale withdrawal seen in Afghanistan recently.

The US invaded Iraq in 2003 looking for weapons of mass destruction, and the number of American soldiers in the country has steadily decreased since then, from a peak of around 160,000 in 2008. The situation has evolved from having the American military as an invading force — welcomed by some Iraqis, despised by others — to the establishment of a series of agreements between the US and Iraqi governments that allowed troops to remain under certain conditions.

In 2011, under President Barack Obama, these agreements saw US troop numbers decrease. In 2014, US troops returned to Iraq again, at the country's request, to lead an international coalition against the "Islamic State" group, which had taken control of large parts of northern Iraq. Since the Iraqi government officially declared victory over IS in 2017, troop numbers have fallen again.

Today, there are around 2,500 US soldiers in Iraq, along with about 4,500 Department of Defense contractors. There are also around 1,000 soldiers from the other coalition countries stationed in Iraq. About 130 are from Germany.

No end in sight

Even after the recently announced transition, US troop numbers are unlikely to change much, US Department of Defense spokesperson John Kirby confirmed at a press conference earlier this month. "This is a change in mission, not necessarily a change in physical posture," Kirby told journalists. It was a "natural evolution" based on agreements made with the Iraqi government and work that had already been going on for months, he explained.

There wasn't going to be any sort of ceremony to celebrate the transition, Kirby added, and there wasn't currently any end date for the new training mission.

"The US has been in a non-combat capacity in Iraq for some time now, if not a number of years," Ranj Alaaldin, a non-resident fellow at the Washington-based think tank, Brookings Institute's foreign policy program, said recently. Alaaldin pointed out that announcements like this have been made several times already.

Ongoing changes

But there have been some changes, and these have been ongoing. US troops pulled out of eight bases that they thought might be vulnerable to attack by the PMF, Caroline Rose, a senior analyst at the Washinton-based think tank, Newlines Institute, told DW: "We saw a series of base transfers, but they were kept quite quiet."

According to a November report to the US Congress on the mission in Iraq, one command post was moved from Iraq to Kuwait in November and another was recently downgraded in terms of seniority in military leadership.

Some US contractors, such as those involved in maintaining Iraq's fleet of F-16 fighter jets, have been relocated and are now working remotely. Most Americans are now based in either Baghdad or the northern city of Erbil. Two thousand military vehicles were recently handed to local staff, and US funding for some aspects of the military cooperation has been gradually decreased; the Iraqi government is expected to take these costs over eventually.

The report prepared by the US military also noted that of 426 anti-IS group operations carried out by Iraqi counterterrorism forces between July and September, only 13 involved a partnership with coalition forces. The international coalition also conducted fewer airstrikes against IS group targets in those months than it previously had.

The report also suggested that the US' rapid withdrawal from Afghanistan had an impact on how quickly Iraqi officers were moving to become more independent.

Aviation assistance

"In practical terms, we still need US forces here, particularly when it comes to air cover and combat aircraft," a senior source inside the Iraqi government recently told DW; they had to remain anonymous as they did not have permission to speak to media.

"The Iraqi air force is comparatively weak, and if it wasn't for the US Air Force, the country would be far more vulnerable to external drone attacks, and it would also have difficulty mounting aerial attacks on the IS group," the source said. "The Iraqi military also needs the US' intelligence on the IS terrorists."

The report to US Congress confirmed this several times. For example, it said, "[US] aircrafts' better sensors … allow them to fly at higher altitudes. Iraqi [planes] fly at around 10,000 feet during their missions, potentially alerting surveilled targets."

US planes are likely to continue to fly sorties against IS, as well as undertake surveillance.

Economic crisis

In other ways, the change in status of US troops is indicative of the ongoing change in US policy toward Iraq, especially when compared with the Trump administration, Brookings Institute analyst Alaaldin said. "With this current [Biden] administration, the Iraqis are hoping for a more delicate, more moderate approach to the country, and understanding that the security climate in Iraq is tied heavily to the domestic political dynamics in Iraq," Alaaldin argued.

While it is an important partner in Iraq, helping to balance internal and external political forces, the US cannot solve all of Iraq's complex and pressing problems, Sarhang Hamasaeed, director of Middle East Programs at the Institute of Peace in Washington, wrote in a July analysis. Some of the country's biggest concerns right now are economic, Hamasaeed explained.

"Even if it may be more limited than what the Iraqis want, an Iraq-centric policy may evolve under the Biden administration that's not seeing Iraq purely through the lens of Iran and IS issues," he argued.

"I think that the [IS group] will always play a role in US policy in Iraq, as will the quiet understanding that US troops provide a counterweight to Iran," Rose, the Newlines Institute analyst, concluded. She added that there had been a recent and worrying uptick in extremist activity.

"But the other aim is capacity building in areas like law and order to ensure that Iraq doesn't devolve into a power vacuum, a situation that the IS group could exploit."