The Iraq war is the first American war to rely heavily on the use of mercenaries. Recent Iraqi accusations against Blackwater have highlighted this problem. Where once the US would have protected diplomatic personnel by use of soldiers, now it relies on mercenaries such as those managed by Blackwater. And the US has given them immunity from prosecution by either US law or Iraqi law. There are many articles on-line about this problem.
The LA Times reported in January:
At last count, there were about 100,000 contractors in Iraq, of which 48,000 work as private soldiers, according to a Government Accountability Office report. These soldiers have operated with almost no oversight or effective legal constraints and are an undeclared expansion of the scope of the occupation. Many of these contractors make up to $1,000 a day, far more than active-duty soldiers. What’s more, these forces are politically expedient, as contractor deaths go uncounted in the official toll.
See also this transcript from “Democracy Now.”