I understand why NATO and the USSR were opposed to each other in the context of the ideological battle of the cold war, but why did they keep being in opposition after the collapse of the USSR? In particular, why is there a focus on preventing Russian expansion compared to that of other countries? Did Russia keep an expanding imperialist tradition?
I apologise if these questions seem very silly, but international politics aren't my thing by a long shot, so I'm trying to understand it from a historical point of view.
There was much cooperation between the west and Russia after the collapse, Russia was even a NATO partner at one point. Unfortunately after Yeltsin left and Putin and his KGB posse took possession of power and created an authoritarian grip of the country. There are decisions the west made that Putin took personally and made many small aggressions towards the west. This is probably a terrible explanation but I highly highly recommend the book Putin’s People. Great book, I listened to it on audible.