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room101 Yeah, I remember reading a biography written about Putin. He was in the KGB stationed in East Germany when the wall came down. From what is written, it seems like it had a big effect on him. He scrambled to burn documents and wracked his brain trying to understand why the East Germans would revolt against USSR leadership. He might have even truly believed they were there to help the East Germans, even if they sometimes had to use unpalatable methods. (Though I doubt he himself would ever speak of his true feelings on the matter such that the public could ever hear.)
It seems to have triggered a period of introspection and learning for Putin, as he came to realize that they weren't there to help the East Germans or expand the ideology, not anymore anyway, they were there to defend and enrich the Russian heartland, as was the entire Soviet Union, and he crystalized the doubts he had been fostering about communism, paving the way for the oligarchic kleptocracy he would later sit atop of. These doubts of course were not uncommon in the Soviet Union, particularly among the educated, but none would match Putin in the sheer magnitude of ideological reversal. At least, none that we can see. The Soviet Elite knew the system was failing, and focus turned away from trying to fix it, toward seeing how much they could get out of it before the ride ended.
He also fostered a deep distrust of the west, and feelings of betrayal. Though I think over time those feelings have softened in intensity, there are material reasons he knows he can never take up a handshake from the west in fully good faith.