This introduction presents an overview of key concepts covered in the subsequent chapters of this book. The book provides both a description and an explanation of the foreign policy of Russia. It explains the similarities and continuities of Russian behavior in large part as a consequence of the international system, which conditions the foreign policies of all states. The term polarity commonly is used to describe the structure of the international system. There was no Cold War between the Soviet Union and the West before 1945 for the basic reason that international politics was multipolar and not bipolar. Diversity in the political, economic, and cultural development of all countries is becoming firmly established, and the role of forces that favor peace and broad international cooperation is growing. Sometimes the term 'anarchic' is used to describe this feature of the international system. Together they reflect the fact that foreign policy has its roots in both domestic and foreign forces.