Russia has plenty of energy, a large population, and plenty of lebensraum. They are very vulnerable to insurrections from ethnic populations living under Russian rule. Having bordering states with kinfolks under Russian rule across a rugged frontier and uncertain border makes Russia uneasy.

Think of Spain & Basques and then multiply that by literally dozens of ethnic minorities. Russia sees Georgia as a threat.

Also, Russia reminds everybody in Europe where their energy comes from -- the Rodina.

B