The concept of mercenary has been used during the history of man to refer to those non- nationals who enter the war for personal benefits; however, the term has changed over time. Currently, there is talk of the privatization of security because there are private security companies that, as temporary employment agencies, offer their professionals, not only to fight but also to protect mining or oil facilities, to form national armies and even to escort humanitarian assistance in situations of civil war. It is intended then, to identify if the hiring of these security companies threatens or diminishes the concept of modern State. To strength the debate, it will be used as an example the hiring of private armies by the United States for the war with Iraq that began in 2003.