The comment talked about "world revolution" and a "wide spy network" so it was not immediately clear to me that the infiltration you were taking about where only on domestic soil like what the article was about.
USSR had very wide spy network and they had considerably infiltrated US.
China was also overtaken by communists and had some influence among some naive Western intellectuals but I don't know about direct influence in US (maybe it existed, I'm just not aware of it).
These days of course both Russia and China are actively attempting to extend their influence through spy networks or by manipulations in social media (and yes, there are also obvious shill accounts here).