Russia objects to Ukraine being independent. It has object to Ukrainian membership in the EU, and has insisted it be a “satellite” state, and object to free elections in Ukraine. And to make it clear, the have invaded the country several times.
Non-interference and non-use of military force has been the based of European relations and has brought peace to a region that had been wracked by warfare. By breaking treaties guaranteeing Ukrainian independence and starting a war, Russia serious told the European to either submit to Russian domination, or be prepared to fight for your independence. Much to Putin’s horror, the Ukrainians and the Europeans are willing to fight.
Biden definitely misled Putin by surrendering in Afghanistan, and Putin thought that the US had sent a message that it would not object to tyrants conquering their neighbor.