At the Joint Base Balad-Iraq in, April 2009, the security force used for most of the routine, boring security jobs on base is the Ugandan Guards.
These are contract employees from Uganda. They are young folks who all formerly served in the Ugandan Army at some point. In order to make more money, they sign up to do security work for a contractor, and they come here to Iraq. The average pay is about $600 to $1,000 a month, which is a very good income considering the alternatives in employment in Africa. When it was more dangerous in Iraq, they were paid more, nearly double their current pay. They are not mercenaries, and are never sent out on missions.
Here's a picture of the Ugandan Guards playing pool on the base during their off time.