Putin's actions follow the authoritarian invader's playbook almost to the letter. He took Crimea in 2014, following that with Georgia in 2019. Last month, he occupied Belarus with its puppet president claiming that it was at his request. Yesterday, he "freed" two provinces from Ukraine. Two hours ago, he begin hitting military targets within Ukraine itself, warning any country that interferes that they will see a retaliation unlike anything in history [i.e. nuclear warfare].
Putin, like Hitler and Napoleon before, expects the other powers of the world to roll over and accept this act of aggression. We know from history that a strategy of appeasement does not work; it only makes the aggressor hungrier for more. The world must stand together and bring an end to Putin's ability to wage war--whether through economic or more drastic measures.