No kidding? Russia recently invaded, conquered and illegally annexed the mineral rich Crimean peninsula. All with the support of the Russian Orthodox Church, which in my opinion is more nationalist than it is orthodox.
Actually I think that’s more or less historically backwards. Crimea has been historically Russian since being conquered from the Turks. The population is more than 90% ethnically Russian and Crimea has no real history of attachment to Ukraine. It only became part of the Ukrainian FSSR when Nikita Khrushchev arbitrarily redrew the administrative map of the USSR in the 1950’s. (Khrushchev was Ukrainian.) It’s been a sore point both with Russia and the people who live there almost all of whom wanted to remain part of Russia.
A more serious issue is Russia’s invasion of Eastern Ukraine, where the population is mixed and there is a much stronger historical claim favoring Ukraine.