Churchill ordered 'Operation Unthinkable' at the end of WWII which was a surprise attack against the USSR. The plan was abandoned because Soviet troops outnumbered theirs 4-to-1.
The cold war was a period of over 30 years of tension between the Western and Eastern blocks, which was essentially NATO against the USSR and its allies.
The Cold War almost never happened, though.
Winston Churchill ordered “Operation Unthinkable” at the end of the Second World War. This operation was initially going to be a surprise attack against the Soviet Union immediately following the end of WWII.
The goal of this operation was to "impose the will of the Western Allies" on the Soviets and force Joseph Stalin to honor the agreements in regards to the future of Central Europe.
If this had happened, there was a good chance of an all-out war with the USSR.
The Soviet numerical superiority was roughly 4:1 in men and 2:1 in tanks at the end of hostilities in Europe.
They were supposed to attack the Japanese, but since they hadn’t yet, many allied countries were worried that Stalin was a threat to Western Europe.
The odds were deemed too steep to risk the attack, so the operation was abandoned. The only advantage the West would have would be the element of surprise, and if that didn’t work, another big war would be inevitable.
The soviets would also be able to ally with Japan since they had not attacked them.
The code-name for the operation was then reused for a contingency plan set in place to guard against a Russian advance on Europe. This became the first of the Cold War-era contingency plans for war with the Soviet Union.
Both plans were highly secret at the time of their creation and it was not until 1998 that they were made public.