It's a huge and growing industry -- up to 180 companies are estimated to be operating in Iraq, some with contracts worth millions of dollars.
It's also a dangerous job. In Al-Fallujah this week, four security contractors were shot and burned in their cars, their mutilated bodies dragged through the streets. They were working for a U.S. firm, but many are employed by British companies.
Christopher Beese works for ArmorGroup, which has staff in over 30 countries. He says the work in Iraq is not so different from providing security in other parts of the world.
"In Iraq to secure the interests of civilian contractors we supply security officers as escorts. The conditions in Iraq mean they will necessarily be armed, for the minimum required to protect against the threat. But it's not much grander than that, it is commercial security albeit at the heavier end," Beese said.
That means selecting routes and ensuring safe travel to and from work for civilian contractors working on the reconstruction of everything from schools to power stations and oil fields.
But while the work might sound similar to that done by private armed security guards worldwide who -- for example, transport cash for businesses and banks -- the fact that it is being done in Iraq raises special concerns.
The contractors sometimes openly carry weapons, and some Iraqis might confuse them with U.S. and U.K. forces. And while ordinary soldiers operate under strict rules of engagement and tight military command structures that regulate where they go and how they act, the security guards are not as constrained.
There are some indications that the four security guards killed in Al-Fallujah were mistakenly targeted as U.S. forces. U.S. officials say the attack in Al-Fallujah appears to have been preplanned. And some military analysts have suggested that the security contractors offered particularly vulnerable targets because they were operating without the kind of intelligence information, communications, and backup forces used in U.S. military operations.
Now, as the Al-Fallujah killings have generated some of the most horrific images of the yearlong occupation, the deaths of the security men are forcing Washington to make difficult policy decisions about how to respond.
The spokesman for the U.S. military in Iraq, General Mark Kimmit, said yesterday that U.S. forces will hunt down those who carried out the killings in Al-Fallujah unless city officials arrest those responsible for the murders.
"If we can get the city [Al-Fallujah] leadership to come out from behind their desks, tell us who these people are [who were involved in the killing and mutilation], identify who these people are and, even better perhaps, imprison these people themselves, we can avoid a direct conflict," Kimmit said.
Beese said the security contractors are not in Iraq as soldiers and should not be confused with them. He, like many in the security industry, rejects any labeling of the armed guards -- many of whom are former special-forces members -- as "mercenaries" or soldiers for hire.
"None of us would see ourselves as mercenaries, we provide security services under normal commercial agreements in support of an internationally supported reconstruction program. To call people mercenaries is erroneous and misleading. Some may see it as an opportunity to have wages at the higher end of their profession, but at the moment there is significant demand in Iraq for commercial security and these people see it as an opportunity they'd like to seize. Professionally they like the challenge, they believe it's something worth doing, and the rates are good. But I don't think we can look at it as a gold mine for them, they take it very seriously and the word mercenary honestly doesn't apply, it's erroneous," Beese said.
A security contractor with a special forces background can earn as much as $500 to $1,000 a day in Iraq.
The sight of so many security contractors working in Iraq with no clear rules of engagement has generated some criticism of the practice.
Michael Page, who works for International alert, a London-based NGO promoting conflict resolution, said the security industry needs to be better regulated.
"We need to move towards the principle that arms experts should be treated the same as arms exports, that is if you're providing military services, even if you're not providing military hardware you should have licensing that's very similar to the current EU code of conduct on arms exports," Page said.
Others are uncomfortable that the private security companies are doing jobs that used to be done by the military.
David Claridge heads Janusian, another London-based security company. He said the Al-Fallujah incident might have some dampening effect on recruitment or -- at least -- lead the security companies to now reevaluate how contractors work in Iraq and find ways to better control their operations.
"It may have an impact in terms of discouraging some of those people who are seeking to go out to Iraq to make their fortune with security companies but perhaps don't have the appropriate skills to work there. I think the security community as a whole will be watching with interest what the implications of this tragic even have been in terms of tactical lessons to be learned but generally speaking the industry acts together in sympathy for those who died and feel that work should go on," Claridge said.