Although they were allies during WWII, the United States and the Soviet Union, fueled by their fundamental ideological differences, embarked on what would be called the Cold War starting in the post-WWII era. As both sides would eventually have nuclear and atomic bomb technology which potentially spelled the end of the world if used, both sides instead largely used propaganda to win the Cold War. The propaganda was both official (i.e. issued by the government) and unofficial, and was designed to make its own side look good while making the other side look bad. The propaganda was aimed to its own citizens, to the other side and to others around the world, who were often looking to the two superpowers for support. One problem often was that the propaganda had to match the reality that people saw and faced on the ground.