Geostrategy is about more than just invasions. It's about military assets, natural resources, artificial resources, trade routes, cultural influence, the ability to attack from and defend certain geography and plenty more I didn't name. And it's more than Russia playing the game.

It's not a national defense strategy, it is a national security one. They need to control the paths for gas exports to Europe to maintain Europe's reliance on them for heat in the winter. It makes them powerful.

If you look at national strategies for nations and territories, even beyond the time the current state has ruled, for every major or minor power throughout history, you'll find similar strategies because the underlying realities remain the same.