Because we're a threat to the imperialist world system that NATO was formed to uphold.
NATO is a military alliance built of the major imperialist capitalist powers and that organization works tirelessly to uphold the standard of global capitalism. Communists don't tend to like that.
I posted this earlier, but it's still relevant, and really sums up attitude the US and NATO had during gladio:
CW SA, misogyny:
spoiler
In Greece during the coup "the US ambassador in Athens, Phillips Talbot, complained to Maury ((Athens CIA chief) one week after the brutal change of power that the US coup represented 'a rape of democracy'. Maury answered: 'How can you rape a whore?"
ShowFor me it's all the posturing like the west is about 'freedom' and 'democracy' when this is the actual history.
Because communists are not self-destructive, at least on a international scale.