As another pre-war take on the situation, I found this 2014 Chatham House panel discussion to have some really interesting perspectives: https://youtu.be/mxn_DdshwCc. Among the panelists are John Mearsheimer (arguing that NATO behaves irresponsibly by expanding in Eastern Europe) and Michael McFaul (arguing that Mearsheimer's cold war diplomacy does not fit the 21st century). A very interesting exchange.