You raise a good point. In times of emergency, desperation: nationalism can be beneficial.

For the most part however it seems to be destructive.

It is quite sad the propaganda machine has convinced many that Ukraine hasn't done anything wrong at all. I am still catching up with a lot of the recent history in the region.

https://en.wikipedia.org/wiki/War_in_Donbas

https://en.wikipedia.org/wiki/Minsk_agreements

https://en.wikipedia.org/wiki/Azov_Battalion

I am certainly not saying that Russia didn't take advantage of the situation here. But as always the situation is much more complicated than what is typically presented.