It started well before 1950. During WW1, the Communist Revolution resulted in a peace treaty with Germany that threatened the Allies chances of defeating Germany. When the atrocities of that revolution became known (including the execution of the Tsar and his family), the US, France and Britain sent military units to Russia to assist in a failed counter-revolution. After that, the seeds of mistrust were firmly planted, and the attempted Communist invasion of Poland provided the fertilizer.
This animosity continued until the USSR became Britain's best friend after it was attacked by Germany in 1941. (No problem that it had also invaded Poland in 1939!) After Churchill recovered from his fixation on killing as many Germans as possible during WW2, he finally realized that the USSR was a far greater threat to his country's dwindling empire.
The US had its own reasons to fear and loathe the USSR after it was discovered that its revered atomic scientist were Communist agents or dupes, depending on one's point of view. This embarrassment led to a nationwide campaign to paint the Russians as depraved monsters doing the bidding of their insidious but insane leaders. As a result, the US decided that it could only deal with the Russians through threats of brute force or annihilation.
We have continued with that mindset to the present day by presuming that any Russian national concern is merely a camouflaged attempt to restore or expand its empire. Doesn't that sound familiar?