This. Full stop.
I've negotiated with plenty of irrational, maximalist opposing parties. And once they have given you enough indications that is their approach, your only appropriate response is "fine. You know how to reach us when you're ready to talk."
Then, you do two things. First, you stand fast against everything they throw at you. Don't back down. Second, counter-attack and score some wins: bloody their nose.
Opposing parties like this don't come to the table until their pain threshold is exceeded. It is the only thing that will motivate them to seek a deal. Any moment until then doing anything else -- and any moment that you are not devoting to doing the only thing that will advance the ball (that is, punching them in the nose repeatedly) -- is a waste of time.
Russia will deal either when Russia breaks/Putin dies, or when the pain becomes too much to bear. And they can bear a lot of pain, so you need to inflict a lot of pain. Well-to-do Russians freezing in their apartments in Moscow this winter, that sort of shit, is how you advance the ball.