Define “lose”.......I do not believe it is possible to occupy all of Russia, Napoleon and Hitler found that out the hard way.
“Define “lose”.......”
A radiated world...
Nuclear winter...
A Billion dead...
Things like that.
China will occupy Russia up to the Ural Mountains. If Europeans are too legalistic to overrun European Russia, Turkey and the Central Asian stans probably have zero qualms. What remains after an all-out nuclear war may have Russian genes, but will probably speak either a Turkic language or Mandarin Chinese.