Nor should it matter to Russia, because all of this happened not in Russian territory.
Which changed when Donetsk and Lugansk have declared themselves autonomous and asked Russia for assistance against Ukraine's attacks.
Under international law, Russia is not the aggressor as the "right of self-determination of peoples" is usually held in such high esteem. In my view, the attack came from Ukraine and the 2 republics have asked for "assistance" against a genocide that has been going on for 8 years and intensified in 2022. There is no right of a state to wage war on parts of the former state entity, to murder them and to raze their dwellings to the ground. I assume that exactly at this point the "international law" was massively broken on the part of Ukraine, only... only no one in the West was bothered by it. Pathetic.
Has it? The autonomous Donetsk and Luhansk have declared themselves and are only recognized by Russia as autonomous states. In reality, they're simply two Ukrainian occupied territories. How is Russia not the aggressor, under "international law"?
My prediction is this action goes on and on and on and on and on for all of May,June,July,August,Sept, even Oct by then gas will be nuts diesel will be over the moon and the oil barons of the world will be smiling bigly.
So my answer to the op question is Putin/Biden is doing exactly this and will do this for months to come while we all suffer the inflation it causes.
That's my main concern, no one believed that the war would last that long, but it looks that it's not bound to end anytime soon. As you've already mentioned, the war is likely to last till the end of the year, causing excessive oil prices and severely increased inflation rates.