If the civilized world had jointly taken tough measures against the military invasion of Russian tanks on the territory of the sovereign state of Georgia in 2008, then there would most likely not have been a subsequent Russian attack on Ukraine in 2014. In 2014, light symbolic sanctions followed against Russia, because they were afraid to anger the aggressor. This prompted Putin to launch a large-scale invasion of Ukraine in order to take over this state and enslave its people in February 2022.
After the publication of the atrocities committed by the invaders against the civilian population of Ukraine, and also due to the heroic resistance of the Ukrainian people to the Russian invasion, and thanks to the effectiveness of such a rebuff, many states finally realized that indulging the aggressor only increases his appetites. That Ukraine will be followed by the Baltic countries, Moldova, Poland. Now the civilized world has seen that the hands of Ukrainians can put an end to such an aggressive monster, which is Russia, and therefore they began to help Ukraine with serious weapons.
So, I believe that if we had USA of 20023 period, Russia wouldn't dare to do what they did, but we do not have that so they are attacking anywhere they want since they won't be getting any push back from any nation and they know this. Sanctions didn't matter that much neither, Russian economy is still fine.
I don't think so, because the decision for war by Russia seems like broadcasting themselves as a strong nation similar to USA. If not there is no need for a war and Russia have now proved to the world that it can operate even when cut-off from the rest of the world. Even in this war the participation of USA will be there indirectly, because every war is a business for the countries who keep the weapons ready for supply.