It’s the same old BS. USians have never made a convincing case of why or how Russia was supposedly an enemy, apart from lots of ideological handwaving. The adversarial relationship has never had any substance. And even in the 50s-70s US conservatives were eager to use the same broad brush to tar artists, hippies, and anyone else who challenged the local hegemony. FWIW liberals are an easy target because they typically petition somebody else with “real power” for change instead of implementing it themselves. This is why most people think of the left as well-off academics who merely comment rather than a political/social force with any agency.
It goes back at least to the communist and anarchist labor movements of the early 20th century. The liberals were the comfy bourgeois people who were frightened into accepting hollow assurances from heads of industry and finance to police themselves, instead of instituting anything fundamentally different. It arguably hasn’t turned out very well!