There are companies out there that have contracts with the government, but there has also been legal trouble regarding the use of mercenaries and who can be hired for what. You also might not find tons of work within the United States, or you won't find any work at all in the United States. If you haven't served in the military, then this career most likely won't be for you. You simply won't be able to find the contacts to get the jobs.
I know that this job might seem ridiculous, but that doesn't mean it doesn't exist or that it's not a valid profession. There are negative sides to it, but for those who have come out of the military with little other options, this may be the best way to make a living.