In some cases , this has also been the result of the mediating role of the United Nations and , in others , the result of steps taken by the main regional and subregional organizations and of particular countries and prestigious African political figures . The role of the Organization of African Unity ( OAU ) , which is now the African Union ( AU ) , and the role of the continent 's subregional organizations have also been fundamental in this process , as well as has the level of cooperation between the United Nations and those organizations .