The Russia-Ukraine war is a war of conflicting nationalisms. Putin thinks the Ukrainians are just Russians with a funny accent, so of course they should be united with Mother Russia. Zelenskyy thinks the Ukrainians are a separate and distinct nationality, so of course they should have their own independent nation-state. Both goals are perfectly in accord with nationalist principles first articulated in the 19th Century, which provide no grounds on which to decide questions of uncertain or disputed national identity.