The true tension began when each nation began producing weapons of mass destruction. The Soviet Union produced and exploded their first bomb 1949 kicking off the Arms Race. Due to Mutual Assured Destruction both countries never fired at each other.
The Arms Race - US 1945- Explodes 1st atomic bomb. 1952- Explodes 1st Hydrogen bomb 1955- Begins building ICBMs
-Soviet Union 1949- Explodes 1st atomic bomb. 1953- Explodes 1st Hydrogen Bomb 1954- Begins building ICBMs
-Together 1957- USSR tests ICBM capable of carrying an H bomb from USSR to USA