When the Bolshevik Revolution took place in 1917, there was a genuine expectation that the proletariat would rise up in every country and that all of Europe (at least) would soon fall like dominoes. There was genuine surprise and disappointment when this didn't happen. At the same time, many American elite - academics and journalists - were enamored of Marxism and what the Bolsheviks had achieved. Hence, there has always been this Marxist-leaning strain within the ranks of the elite.
The notion of a long march through the institutions, as opposed to a revolution or war, is indeed the only realistic hope for a Marxist/Socialist transformation of a country like America. The educational system is the primary institution for achieving this. I graduated from college in 1972 but did not enter law school until 1979. Just in that time, the change was obvious. There are now 2-3 generations below me who are products of an educational system I don't even recognize.
Over the past roughly 40 years, the changes in American society wrought by the Left have ALL, without exception, been in furtherance of the long march. This is precisely why my USSR-bred wife said over and over again, "My God, this is exactly what the Soviets tried to do!" It has become so pervasive that I don't think many of its promoters - Pelosi, Kamala, AOC, et al. - are even aware that they are pawns in the long march.
It's an ideological march that has nothing per se to do with Russia or Putin. Putin is about as Marxist/Socialist as Trump. This is precisely why, at the U.S. Embassy in 1959, Snyder joked to Oswald that he was going to be a "very lonely guy" in Moscow if he was a Marxist. Trump's affinity for Putin, I believe, is because (1) Trump has an affinity for "winners," and Putin is a wealthy, powerful guy and (2) more significantly, Trump is above all a pragmatist who realizes that America benefits more from a stable relationship with Russia than with an unstable one. It's all about Trump's vision for America, which is pretty much the America I also knew.
What I don't understand is this McCarthy-esque "Russkie mania" of those like Tom. Everything Trump is doing is aimed at halting the long march and dismantling what it has achieved. To me, it's like saying a white guy with a Black wife and two adopted Korean kids is a white supremacist. How does that work?