"Since March 2004, when the charred bodies of four American security guards were dragged through the streets of Falluja, private security in Iraq has become a multibillion dollar business for a handful of US and UK companies. For the hired ex-soldier earning up to $1,000 (£500) a day, it is also the most dangerous job in the world. More than 900 have been killed in the past three years, the majority of them American. The Pentagon estimates there are about 20,000 armed security guards in the country although some observers have put the figure much higher."