Unfortunately for Russia, they have no reputation for honest negotiation. It's a classic case of the horse negotiating with the scorpion which proceeds to sting it as it carries the scorpion across the river. And yes, they could commit suicide with nukes but that could end the Russian culture for eternity and all other cultures will survive because the bulk of Russian culture and history resides in two cities and all other cultures reside everywhere else. Two pinpoints on the map vs. the map. Russia knows this is not a viable option but talk is cheap and used in brinkmanship.