After World War 2 USA and USSR unite in the victory of defeating Nazi Germany. Then the allied nations had a conflict on the different ideologies, Soviet Union was a Communist country, which was ruled by a dictator and put the needs of the state ahead of personal human rights. The USA was a capitalist democracy which valued freedom and feared Communism.
President Harry S. Truman
September 2, 1945
Dictator Joseph Stalin
We will give money and military aid to countries threatened by communism, and effectively stop communists from taking control of Greece and Turkey.
March 12, 1947
USA and USSR have made atomic bombs that created a deterrence which means the action of discouraging an action or event through instilling doubt or fear of the consequences.
WE have made atomic bombs and we are warning you.
During the Cuban Missile Crisis, the USSR and the USA came the closest they had ever been to engaging in nuclear warfare. This is brinkmanship, an attempt to push a dangerous situation as far as possible without conceding to the opponent. In the end, they both removed the missiles.
Get your missiles out of Cuba
President F. John
Soviet Leader Nikita Khrushchev
Then get your Missiles out of turkey
Cuban socialist leader Fidel Castro
Stop your repercussion
After the nuclear threat as a result of the Cuban Missile Crisis, both superpowers became afraid of mutually assured destruction and entered a period of deterrence, or a period of relatively peaceful relations where many treaties were made and the countries engaged in events.
All of this occurrence was unnecessary
Indeed it was prodigiously unnecessary
The end of the Cold War signified better relations between the USA and the USSR, the end of communist regimes in East Germany, the fall of the Berlin Wall or "iron curtain", and the dissolution of the USSR.