One problem of his telegram, at least arguably, however, is the fact that he seems to attribute the aggression of Stalinism not to the principles of Communism, but to the Russian national character:
At bottom of Kremlin's neurotic view of world affairs is traditional and instinctive Russian sense of insecurity. Originally, this was insecurity of a peaceful agricultural people trying to live on vast exposed plain in neighborhood of fierce nomadic peoples. To this was added, as Russia came into contact with economically advanced West, fear of more competent, more powerful, more highly organized societies in that area. But this latter type of insecurity was one which afflicted rather Russian rulers than Russian people; for Russian rulers have invariably sensed that their rule was relatively archaic in form fragile and artificial in its psychological foundation, unable to stand comparison or contact with political systems of Western countries. For this reason they have always feared foreign penetration, feared direct contact between Western world and their own, feared what would happen if Russians learned truth about world without or if foreigners learned truth about world within. And they have learned to seek security only in patient but deadly struggle for total destruction of rival power, never in compacts and compromises with it.
Marxist ideology is to some limited extent to blame for the soviet attitude, but only insofar as the soviets took these ideas and twisted them to suit their own purposes and justify their ideas. In other words, the USSR is an evil empire, but only because of its leadership, not because of any intrinsically misplaced ideas about human nature, etc. (if you don't agree that the ideas are misplaced, I'm not intending to prove anything just now, just observing that that's his position).
After establishment of Bolshevist regime, Marxist dogma, rendered even more truculent and intolerant by Lenin's interpretation, became a perfect vehicle for sense of insecurity with which Bolsheviks, even more than previous Russian rulers, were afflicted. In this dogma, with its basic altruism of purpose, they found justification for their instinctive fear of outside world, for the dictatorship without which they did not know how to rule, for cruelties they did not dare not to inflict, for sacrifice they felt bound to demand. In the name of Marxism they sacrificed every single ethical value in their methods and tactics. Today they cannot dispense with it. It is fig leaf of their moral and intellectual respectability. Without it they would stand before history, at best, as only the last of that long succession of cruel and wasteful Russian rulers who have relentlessly forced country on to ever new heights of military power in order to guarantee external security of their internally weak regimes. This is why Soviet purposes most always be solemnly clothed in trappings of Marxism, and why no one should underrate importance of dogma in Soviet affairs.
Another interesting thing about Kennan is that after writing this telegram and then the essay "The Sources of Soviet Conduct", he basically spent the entirety of a long (but much less illustrious) political career denying everything he ever said here, going around to university campuses and telling people that "well, yes, that's what I said, but what I meant was..."