Putin and Russia have all of Siberia to develop. The only resource they lack is people to do the developing. A big push against Ukraine might end in nuclear war. US nukes are nothing to scoff at, even though Russia's might be bigger and better and more of them. Nukes are a bad idea for the whole world. There probably wouldn't be any developing of Siberia for hundreds of years after a full blown nuclear war. So, like the US, NATO, China, and other countries, Russia is not going to provoke a nuclear world holocaust, except as an absolute last defense. Play the game slowly, and win at it slowly, rather than not winning anything at all.