So give putin want he wants, and when he comes back wanting more, what then?
If it comes down to WW3, then now is the time while russia is weak.
Personally, I have become a fan of assassinations. Catch putin flying and end him. The next russian czar will fuss for a bit, in public, but that would be the end of it.
They aren’t trying to negotiate. The situation in Ukraine is more complicated than you think. There are Russian speaking Ukrainians, who support Putin. This complicates things.