A U.S. Army helicopter brigade is set to pull out of Baghdad in December, as part of an agreement with the Iraqi government to remove U.S. forces. So the armed helicopters flying over the Iraqi capital next year will have pilots and machine gunners from DynCorp International, a company based in Virginia.

On the ground, it's the same story. American soldiers and Marines will leave. Those replacing them, right down to carrying assault weapons, will come from places with names like Aegis Defence Services and Global Strategies Group — eight companies in all.

All U.S. combat forces are scheduled to leave Iraq by year's end, but there will still be a need for security. That means American troops will be replaced by a private army whose job will be to protect diplomats.

Already, the State Department is approving contracts, but there are questions about whether it makes sense to turn over this security job to private companies.