How do you know that Putin wants to rebuild the Soviet Union, it could be that Russia sees Nato as the new Nazis.
Hitler also had his own version of Nato, a lot of these Eastern European countries who are now members of Nato were enthusiastic supporters of Hitler and joined him in his genocide of millions of Russians.
Ukraine is an artificial state, it has had different borders at different periods of history, so why don't they redraw the borders with Russia and let those who want to be Russian join Russia and those who want to be Ukranian stay with Ukraine.
It wasn't the Russians who overthrew the democratically elected Government of Ukraine and kicked off a civil war, the Russians are paranoid about invasion from the West so why should they trust the lying EU or American warmongers like Mc Cain and Co.
You make a good point. During the Second World War, Russia was threatened with annihilation by Germany. After the war, Russia established a string of 'buffer states' between its homeland and West Europe. Having once experienced an invasion of its land almost to the doors of its capital city, I can understand them wishing to do all they could to prevent a repeat performance.
I'm not saying that Russia is necessarily right and The West is necessarily wrong. I believe they are both frightened of each other! There are always two sides to a coin.