realism became the dominant perspective on international politics during the twentieth century, receiving its impetus from the first world war and second world war. these not only undermined the idealist belief in internationalism and natural harmony, but also provided abundant evidence of the naked pursuit of state aggrandisement, especially in the case of Nazi expansionism. During the cold War period, realist theories portrayed global politics in terms of a bipolar world order based upon rivalry between the US and soviet power blocs