During the cold war Era (1945-1990),why were the United States and the soviet Union reluctant/hesitant to become inolved in direct military conflict?

During the Cold War era, the main reason why the United States and the Soviet Union were reluctant to engage in direct military conflict because there was a great potential for global nuclear destruction. ... This gigantic global struggle was known as the Cold War.

Do you have more info about it ? i doubt this is the answer because i don't have all the information but if trouble was brewing in a clinic maybe it was an argument as to which clinic was better or smth of that nature