Funny that I got three replies all stating the same thing, that Russia is the aggressor and has invaded Ukraine. Of course it is so, and then? Russia invaded Ukraine, not the EU. It's the EU that has decided to get involved in the war by supporting Ukraine.
Did you actually read all the posts pointing this and all the _other_ aggressive actions Russia is taking against the EU?
Regardless, Russia is a bully and sticking your head in the sand won't make them go away.
Chamberlain decided not to join the war, look what that resulted in.
Russia (or Putin, to be precise) has repeatedly threatened to invade EU members in the Baltics (rebuilding the SU/Russian Empire/etc), as well as threatened EU with stopping gas supply, which would've been a direct hit to the economy. These two are confirmed facts, there's also a lot more stuff speculated which you can freely find online.