Ronald Reagan
It began in the 1940s at the start of the Cold War.
Mutual Assured Destruction and proxy wars.
It ensures (hopefully) that both nations are too frightened to launch their nuclear munitions.
mutual assured destruction, espionage, detente.
MAD - Mutual Assured Destruction
If you try to blow me up I will blow you up. Nobody wins, so don't try.
The level of nuclear weapons required to completely destroy both sides in any war making use of such weapons.
Mutual Assured Destruction was the military posture for most of the Cold War (1945-1991). It was the concept that neither of the superpowers, the US or the USSR could use nuclear weapons to wipe out the other, because the result would be that both sides were destroyed. To that end, both countries built increasingly large and diverse stockpiles of bombers, missiles, ships, and submarines to insure that a first strike would not prevent retaliation. Each side had to be aware of the other's potential and have the ability to counteract any destabilizing technology. With orbital launchers and anti-ballistic missiles banned, eventually the number of nuclear warheads reached a plateau, and both sides agreed to limitation (SALT) and then to reduction (START), which was underway when the collapse of the Soviet Union in 1991 finally meant a general relaxation in the dangerous stalemate.
Massive Retaliation
Mutual assured destruction
Preventing other countries with nuclear munitions from using them (nuclear deterrence, mutual assured destruction). Or, obviously, to end the world