At the end of World War II and the conception of the United Nations Organization (UNO) as an international organization that had the mission of avoiding new devastating conflicts in the context of the Cold War, Peace-keeping Operations are born with the idea of maintaining peace with a particular objective: to keep peace under very precise conditions and determined tools. Nonetheless, at the end of the Cold War the extent to which the organizations used to work in had to be re-thought since the world scene had been dramatically transformed. There would no longer exist a bipolar tension and the United Stated would be the only superpower and would dictate the guidelines for the International System operation. At the same time, several internal conflicts appear, whether within former colonies in Africa or Asia, or in countries with religious, ethnic or social problems. This meant that a whole new concept of “peace” should run inside the Peace-keeping Operations. At this point the whole system of the Operations was transformed from mere observational missions to multidimensional missions adaptable to all sorts of conflicts, whatever the backgrounds are, with the goal of achieving a lasting and integral peace: one that embraces economic development, respect of human rights and of political and civil liberties, among other elements.