Answer:
the Cold War
Step-by-step explanation:
After the World War II ended, the Allies had different interests, which led to a division between the east and the west. The western countries wanted to establish democracies and market economies, while the Soviet Union wanted to establish communism and command economies. The Soviets also did not retreated from Eastern Europe, but instead had army from their border up to East Germany, practically occupying the whole region and shaping it as they want to, not allowing the people to have freedom of choice. This angered the western countries, especially the United States, so the tensions between the two quickly grew, which started the period known as the Cold War.