Who is to blame for starting the Cold War? The U.S., the U.S.S.R., or both?

I think that both the Soviet Union and the United States are to blame for starting the Cold War. The United States begun to show off their power to the Soviet Union with the atomic bombs dropped on Japan. In turn, the Soviet Union attempted to make their own atomic bombs. The situation spiraled out of control, consequences being huge economical deficits, as well as fear in both Americans and Russians. The Cuban Missile Crisis also caused much fear between the two countries. Both nations were within two hours of a nuclear war, but both sides came to an agreement. Neither country attempted to prevent this crisis earlier, so they both are to blame for helping spiral the situation out of control. Although the United States did make the first move in attempt to show of their strength, the Soviet Union is also responsible for escalating the situation.