The Cold War was a period of geopolitical tension between the Soviet Union and the United States and their respective allies, the Eastern Bloc and Western Bloc, after World War II. There was no direct military fighting, but rather a war of words and growing military buildup as the two nations supported opposing sides in regional conflicts like the Korean War. Key events that defined the Cold War included the rise of communism in Russia in 1917, the end of WWII in 1945 that marked the beginning of tensions, and the division of Germany and Korea along ideological lines. Throughout the late 1940s to early 1990s, the two superpowers engaged in arms races, the formation of opposing alliances like NATO and the Warsaw Pact, and