The mushroom cloud from the atomic bomb dropped on Hiroshima, Japan, by the United States on Aug. 6, 1945.

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The Nuclear Doctrine of MAD

When the atom was split, a Pandora's box was opened. This scientific advancement led to the development of the atomic bomb -- humankind had never before possessed such a destructive weapon. The United States was the first to successfully develop the atomic bomb and the first to show the bomb's level of devastation when it unleashed two on Nagasaki and Hiroshima, Japan. Other nations scrambled to catch up; in the hands of just one country, this technology could arguably give that country control over the rest of the world.

Within eight years, the USSR had its own nuclear weapon -- the hydrogen bomb [source: Murray]. The ideological conflict between capitalism and communism sustained tensions between the U.S. and the USSR, and this prolonged conflict between the nations became known as the Cold War. From 1947 to 1991, the nations built up their nuclear arms, each expanding its arsenal in pace with the other. It was soon clear that both sides had built and stockpiled enough nuclear warheads that the U.S. and USSR could wipe out each other (and the rest of the world) several times over. They had reached nuclear parity, or a state of equally destructive capabilities.

As a result, the nuclear strategy doctrine of Mutual Assured Destruction (MAD) emerged in the mid-1960s. This doctrine was based upon the size of the countries' respective nuclear arsenals and their unwillingness to destroy civilization. MAD was unique at the time. Never before had two warring nations held the potential to erase humanity with the entry of a few computer codes and the turn of matching keys. Ironically, it was this powerful potential that guaranteed the world's safety: Nuclear capability was a deterrent against nuclear war.

Because the U.S. and the USSR both had enough nuclear missiles to clear each other from the map, neither side could strike first. A first strike guaranteed a retaliatory counterstrike from the other side. So launching an attack would be tantamount to suicide -- the first striking nation could be certain that its people would be annihilated, too.

The doctrine of MAD guided both sides toward deterrence of nuclear war. It could never be allowed to break out between the two nations. And it virtually guaranteed no conventional war would, either. Eventually, conventional tactics -- like non-nuclear missiles, tanks and troops -- would run out, and the inevitable conclusion of a nuclear strike would be reached. Since that end was deemed unacceptable by the Soviets and Americans, there was no chance of an engagement that could lead to this conclusion.

But MAD didn’t exactly create an atmosphere in which Soviet premiers and American presidents felt like they could shake hands and call the whole thing off. The nations had very little trust in each other -- and with good reason. Each side was steadily building its nuclear arsenal to remain an equal party in the MAD doctrine. A détente, or uneasy truce, developed between the U.S. and USSR. They were like two gunslinging foes, adrift alone in a life boat, each armed and unwilling to sleep.

So the situation had to be managed. On the next page, find out how nuclear proliferation was controlled.