The geopolitical importance of Russia

According to Mackinder's land power theory, most of Russia is in what he calls the heartland, and it is advantageous for heartland countries to expand to the edge areas of the Eurasian continent. For details, see Mackinder's "Historical History" Geographical Hub.”

The heartland of Russia has a huge strategic radiation effect on the surrounding crescent zone. If the Russian army is highly mobile, the deterrent effect on the surrounding areas will be huge.

I recommend Brzezinski's "The Grand Chess Game", which contains wonderful relevant discussions.