It is a new world. In the Olde Dayz, when you kicked the shit out of a country, killed hundreds of thousands of soldiers, destroyed their infrastructure, killed lots of civilians, "leaders" would see the writing int he wall and surrender. Putin doesn't give a **** about his armed Forces or infrastructure.
In some way, NATO and the U.S. have to figure out a way to attack Russia militarily in a meaningful way, kinda like what Trump did to Iran. Maybe blow up their navy, some power plants, refineries, or a major bridge or two. And when Putin brings out his nuclear threat, just tell him we will vaporize him. And mean it.