Not sure whether Russia "needs" to expand its borders. The money wasted in this war could have been better spent shoring up its position in Siberia and the Far East. That's where most of the country's resources are. Instead, the populations there are packing their bags and moving to Moscow and other places. This leaves the area ripe for being picked off by the Chinese. In fact, the Chinese are raping the resources there as we speak.
Ukraine itself is facing a declining population, just like Russia.
I think Putin's war is driven more by 2 factors:
1) Need to keep power and that of his cronies. Ukraine is a model of a different state. A democratic, pluralistic one. That's a danger to Putin's autocratic rule.
2) He has some weird vision of recreating the old 19th century Russian Empire, and creating a new "Russian World".... whatever that is...
I explain my take on his vision here:
