In fact I'm most surprised and annoyed that some seem to rate this a legal war! No war like this is legal or justified.
Well, I believe
this war is justified, even though I hoped it wouldn't happen. I can explain my reasoning, very simply, by putting you in Russia's position: Imagine that you get cornered in a dark alley, by a clear enemy, who leaves you no exit.
What will you do in this situation, from a tactical perspective?
The
correct tactical move in this situation, is for you to strike first. This is a perfectly valid
defensive action. You can't wait for your enemy to throw the first blow when you are cornered.
Granted, if you find yourself in this situation, it's a failure of situational awareness on your part. Nevertheless, if you do get stuck here, then you have the right to respond with pre-emptive force.
I apply this principle equally and fairly to everyone.
I even grant my enemies this right. This is why I think Israel (whose political existence I don't even recognize) was justified (from a purely tactical perspective) in its 1967 pre-emptive attack. By the way, it's also the same reason that China intervened in Korea. Anyone who is cornered is justified in pre-emptively attacking first as a defensive measure.
So that's why I think this war is justified, even though I was hoping it wouldn't happen.