I think the Ukrainians just need to stop Russia. Even if the Ukrainian armed forces routed them and pushed Russia 100% out of Ukrainian territory it seems very unwise to nuke cities on your border. I guess if Putin and all his generals are literally crazy. I can’t see a victorious Ukrainian army deciding to literally march on Moscow. A full-scale nuclear attack on Ukraine would be such a huge disaster for the world and Russia I can’t see it happening. I’ll keep my fingers crossed.