The fact that USA feared the Sovjet Union (or at least saw it as a big threat) was always given to me as an fact during history class at school. But what was it that made the USA feel so threatened by the Sovjet Union that they started an arms race and made them hate everything that looked like communism?
There are two related phobias at work - one of Communism, the other of a rival superpower.
Communism was never going to endear itself to governing elites in the west (Europe as well as the US), drawn as they were from the more prosperous strata with most to lose and presiding over societies founded on market economics. The "Red scares" after both world wars echoed earlier fears of anarchism and more mainstream socialism, both likewise urging radical social change.
Suspicion and distaste for the USSR were there from its beginning, but outright fear seems best dated to 1947, when western Europe seemed at risk of going the way of the east through economic crisis and associated British abandonment of strategic commitments. Unexpectedly early Soviet acquisition of nuclear weaponry and war in Korea seemed to confirm the threat.
And sections of the US political establishment were only too eager to overstate the danger, whether in the domestic conspiracy-mongering of 1947-54 or by overstating Soviet military capabilities in the 1970s and 80s.
Ultimately much was down to miscalculation or misunderstanding: moves that Moscow saw as essentially defensive were seen - or intentionally misrepresented - in the west as ambitious expansionism, and western counter-measures were likewise seen in the east as aggressive, fuelling a cycle of distrust and escalation.