This is an interesting tidbit from Richard Miniter's firsthand report from the bombing of the Iraqi parliament:
At first, no one could decide who was in charge: the U.S. military, the Iraqi police who actually guard the members of parliament, or the men from Triple Canopy, a private security company based near Dulles Airport in Virginia.
With a bullhorn and sheer force of will, the leader of the local Triple Canopy team, a short thick man in a baseball cap, took charge.
Heavily-armed men from Triple Canopy, mostly Peruvian, escorted every one inside the building into a parking lot ringed with a 10-foot high chain-link fence. This became a holding pen. An American Triple Canopy employee told me that they suspected the bomber may have had an accomplice in the building. Therefore, everyone was going to held and searched.
In the center of the Green Zone, the people actually enforcing security are ... mercenaries. Who controls them?