The Cold War was a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term cold war is used because there was no large-scale fighting directly between the two superpowers, but they each supported opposing sides in major regional conflicts known as proxy wars. The conflict was based on the ideological and geopolitical struggle for global influence by these two superpowers, following their roles as the Allies of World War II that led to victory against Nazi Germany and Imperial Japan in 1945.
International Relations (IR) are the interactions among sovereign states. The scientific study of those interactions is called international studies, international politics, or international affairs. In a broader sense, it concerns all activities among states—such as war, diplomacy, trade, and foreign policy—as well as relations with and among other international actors, such as intergovernmental organizations (IGOs), international nongovernmental organizations (INGOs), international legal bodies, and multinational corporations (MNCs).
Soviet empire, also referred to as Soviet imperialism, is a political term used in history and Sovietology to describe the actions, influence and hegemony of the Soviet Union, with an emphasis on its dominant role in other countries. In the wider sense, the term refers to the country's foreign policy during the Cold War, which has been characterized as imperialist: the nations which were part of the Soviet empire were nominally independent countries with separate governments that set their own policies, but those policies had to stay within certain limits decided by the Soviet Union.
International relations theory is the study of international relations (IR) from a theoretical perspective. It seeks to explain behaviors and outcomes in international politics. The four most prominent schools of thought are realism, liberalism, constructivism, and rational choice. Whereas realism and liberalism make broad and specific predictions about international relations, constructivism and rational choice are methodological approaches that focus on certain types of social explanation for phenomena.
The Second Cold War, Cold War II, or the New Cold War are terms that refer to heightened geopolitical tensions in the 21st century. They have been used to describe the tense relations between the United States and China and, similarly, between the United States and Russia, the primary successor state of the former Soviet Union, which took part in the original Cold War. The terms are sometimes used to describe tensions in multilateral relations.