The United States began developing nuclear weapons out of fear that the Soviet Union and other countries like France and China were doing so. The U.S. became the first to use nuclear weapons when they bombed Hiroshima and Nagasaki in 1945. Seeing the Soviet Union as its main enemy, the U.S. focused on intercontinental ballistic missiles that could travel long distances. By 1957, the U.S. had developed missiles that could fly over 6,000 miles and land within a mile of their target. The nuclear arms race between the U.S. and Soviet Union during the Cold War involved both sides developing capabilities to launch devastating attacks even after suffering assaults from the other side.