Whatever. But your blather — and by the way, “just cause” is not up to your eyes to determine — is totally irrelevant to the following question:
Russia is at war with Ukraine. Europe is arming and aiding Ukraine. Is that not provocation in and of itself?
“Whatever” means that you are unwilling to go there?
But this is the heart of the matter.
And yes indeed, a “just cause” is critical. And it is our personal responsibility to determine that. That question (along with a host of others) is why St. Thomas wrote his “Summa”, to help logically and practically determine right and wrong.
Look in your heart, and look for guidance.