I am not at all surprised by such behavior, because Serbs are brothers to Russians (by religion) and by weapons. If we remember what Serbs did from 1991 onwards in Croatia, Bosnia and Herzegovina, and Kosovo, then it is no different from what their Russian brothers do in Ukraine. What is far more dangerous at the moment is Russia's support for the secession of Republika Srpska, which wants to be part of Serbia, which without a doubt starts a new war in the Balkans.
Interestingly, both Russians and Ukrainians are Orthodox. Majority of the population is orthodox, making them even closer than the Balkan peoples where we have two major religions and the fourth less-represented one. The situation in Bosnia and Republika Srpska is a bit different now than it was back in the 90s. There is no JNA anymore to provide the needed firepower. People got burned by all their political and religious representatives of the past and the atmosphere doesn't smell of war. Not yet at least. Those who are educated and qualified are looking to leave the region to have better lives in Western countries. This is common to all the three countries, people, and religions.
I came across a few posts on social media where some individuals are renting out parcels of their land to the Russians to place their artillery to point towards NATO nations if such thing becomes necessary. Not sure how authentic those are or if people are just joking around and sharing propaganda. Pathetic and sad.