Containment, and with it the maintenance of the post ww2 order is EXACTLY what, from a USA point of view, aid to Ukraine is about.

The past 14 months have buried the previous world order of sanctity of state borders, but hope for preventing Russia from a revisionist subjugation of her neighbors still exists.

Russia began as an expansionistic empire (Tsarist), bent on subjugation and tribute.
Lenin envisioned spreading the Revolution at least to the North Sea.
Stalin turned the Revolution inward. Concentrating on "Socialism in one State".
Hitler gave him vis Molotov- Ribbentrop eastern half of Poland.
Defeating Germany in ww2 lead to Russian empire expansion into central Europe. Stalin redraw national borders at the end of the war.

Kennan correctly understood that Stalin did not share Lenin's vision. Hence containment possible. Due to this he didn6 think NATO, and long term USA presence necessary. He didn't seem to consider how important NATO was in making a future stable Western Europe. Without this stability the free market trust required for the Marshall plan to work could not develop.

Putin has correctly identified the unity of the EU and NATO, backed by mutual values of the Atlantic Charter as the principle obstacles for his reestablishing the Russian Empire of at least Catharine, and possibly of Stalin's Yalta agreements.
He is once again an expansionistic Tsarist.
Kennan correctly assessed that Stalin was not.
Kennan understood that Stalin viewed NATO as a threat.
I strongly suspect that he would have understood that Putin DOES NOT view NATO as a threat, but rather as an IMPEDIMENT.

Threat versus impediment is the key difference on which these threads keep going round and round upon. You are intelligent enough, and open minded enough, to grasp the difference between the USSR that Kennnan knew and the diminished and resentful Russia of post 1991.