They can't. An unbiasedly simple answer. Strategically this war is a lost cause for Russia, even if they win militarily in the short term. Capture is one thing

They can't. An unbiasedly simple answer. Strategically this war is a lost cause for Russia, even if they win militarily in the short term. Capture is one thing. Holding on is another. According to latest estimates, RU has already invested the lion share of its military assets (not army men) in the Ukraine invasion. And they're doing badly. There will be attrition & guerrila warfare if boots stay on Ukrainian soil. They dont have an economy like US/UK to back this up well. They're bleeding under sanctions. Economy is falling as fast as when USSR collapsed. No major foreign trade possible (except the Southern hemisphere countries, China & India) & companies are pulling out. Mass unemployment & currency devaluation will likely follow. The world opinion is not sympathetic to Russia. It is a lose-lose. As of now the Russians are fighting for the sake of one man's inflated ego of building the 'Historic Russia'. The Ukrainians may or may not win this offensive, but they have showed remarkable heroism & solidarity to keep the country fighting.