The main reason America decided to get involved in starting the Cold War was to try to contain communism. During the Cold War, the United States’ weapons arsenal was extremely built up. Demonstrating the new powers they have obtained after the Manhattan Project, America showed that it was ready to be the matchless superpower of the world ("Cold War."). However, the Soviet’s were not ready to give into that thought just yet. The Soviet’s built up their arsenal as well trying to scare Americans.