Answer:
THE COLD WAR
The arms race was merely the United States battling itself. Yes, the Russians had nuclear weapons, but as we learned when the Soviet Union collapsed, the Russians had significantly less military power than what has been assumed. In retrospect the US government should have recognized that fact well in advance solely because of the impoverished state of the Soviet Union...much like we should have realized that Iraq didn't have the capacity to purchase or produces weapons of mass destruction.
Adolf Hitler also predicted the Cold War when he said "... there will remain in the world only two Great Powers capable of confronting each other -- the United States and Soviet Russia. The laws of both history and geography will compel these two Powers to a trial of strength, either military or in the fields of economics and ideology. These same laws make it inevitable that both Powers should become enemies of Europe. And it is equally certain that both these Powers will sooner or later find it desirable to seek the support of the sole surviving great nation in Europe, the German people."
FUN FACT!
In 1958 a US B-52 bomber accidentally dropped an A-Bomb in the back garden of a S. Carolina home. The bomb did not explode