So, in your view, Ukraine cannot decide what to do because else Putin would not feel "secure" despite having a nuclear arsenal? Just think of it in in the opposite way: "Russian should demilitarise so that Ukraine feels secure". You see how absurd that is?
I'm not saying that we're living in a perfect world...but seeing USA/NATO track record since WW2, can you blame Russians?
Looking at Napoleon, Hitler, Genghis Khan and numerous other invasions, can you blame Russians?
I sugegst you look for and watch Oliver Stone (lenghty) interview with Putin on Youtube