The Soviet Union and the United States were involved in a complicate interplay of ideological, political, social and cultural factors, which wavered between open rivalry and cautious cooperation. Their relationship was fluctuating. Antagonism was accompanied with developing convergence. The main issue of this anthology is to discuss the attractiveness of polarity. Differing from Europe as well as from other parts of the world, both powers were provided with their history to expand their frontiers in the 19^th century. Territorial expansion and the discovery of new ideas and ideologies laid the foundation for their geopolitical hegemony in the 20^th century. International authoritative scholars from the United States, Switzerland and Germany give fresh insights in a new understanding of 20^th-century geopolitics.