What is the actual difference if he did?
Boots on the ground immediately?
Wow. You are soooo out to lunch.
Perhaps you are not aware, Jane, but the US is treaty bound to defend any attack on NATO countries with the immediate and direct intervention of US troops. We have had that pledged obligation, by signed treaty, since 1949. If putin attacks a NATO country we have no choice.
That is why it is vital to stop putin
before he attacks a NATO country. If he is not stopped in Ukraine, he will only be emboldened. He will be so much closer to his ultimate goal, there is no way he would stop then.
Yes, even though his military has proven to be incompetent, he still believes he has one advantage over the West. He believes his advantage is a higher tolerance for loss of life. He doesn't care about the hundreds of thousands of russian lives he wastes any more than the hundreds of thousands of civilian lives he has wasted in countries like Chechnya, Georgia, Crimea.
He hopes he can drown the West in enough blood on both sides that the hand wringing "Useful Idiots" in the West to call for giving what ever he wants just to stop the killing. Then he moves on to the next target.
Wash, rinse, repeat.