It is the right of any sovereign country to freely join any military alliance, including NATO. The fact that this upsets Putin says more about him than the alliance and its (potential) members.
"Let me return to NATO enlargement. .... Russia is European and multi-ethnic. I can imagine us becoming allies. Only dire need could make us allied with others. Bit we feel left out of NATO. IF Russia is not part of this of course it feels left out. Why is NATO enlargement needed? In 1954 Russia applied to join NATO. I have the document. [ Bush: "that's interesting" ] NATO gave a negative answer with four specific reasons. Lack of an Austrian settlement. The totalitarian grip on Eastern Europe. And the need for Russia to cooperate with the UN disarmament process. Now all these conditions have been met.Perhaps Russia could be an ally."
Russia is threatening a direct military invasion to present-day and potential future NATO and EU members. When has the EU done the same to any of your listed countries/territories? When have the US said they will invade a country for simply allying with Russia or the BRICS?