No one knows for sure, but it's believed that as much as 40% of the military budget goes to private contractors including private armies.
There are thousands of private mercenaries operating on behalf of the US in Iraq and elsewhere around the world. Nearly 1,000 have been killed in Iraq alone, but their casualties are not counted. Nor has Congress been able to discover exactly how many mercenaries the US employs there.
One of these firms, Blackwater USA, a big supporter of George Bush, is now deploying in the US. They were present in New Orleans after the levee collapses.