The rise in American troops based in Iraq over the same period was significantly less, from 2,300 to 3,700.
Rick Brennan, a retired Army officer and military analyst, explained to Defense One that in the 1980s the US military hired contractors to perform “all those other things that go with maintaining troops in the field for a long time.”
Contractors are engaged in logistics, security, transportation, construction, communication support and training, as well as the management of those aspects of military service.
According to Defense One, state agencies such as the CIA and other private mercenary companies including Academi (formerly private American military company Blackwater), keep using contractors for unspecified close-to-battlefield jobs. The number of those contractors and US-paid mercenaries who are closer to combat than US advisors is classified.
Additional information regarding military contractor use in the US campaign in Iraq in 2007 has come to light, including the incident of US contractors working for Academi — when it was called Blackwater — murdering 17 civilians in revenge killings in Baghdad. Congress subsequently demanded that the Pentagon provide detailed information on the number of battlefield contractors.
According to US Central Command, as of July 2008, some 162,428 Pentagon-funded contractors were deployed in Iraq.