You can't use creeping determinism to explain Russian aggression from 2008 onwards. The invasion of Ukraine, with the subsequent annexation of Crimea and the South Ossetia war are nothing like your theoretical NATO invasion of Tajikistan or viewing Belarus as aggression towards NATO.
On the subject of an intrinsic spehere of influence - no country has that but certainly some acts are provocative. Why you cannot see expansion of a US-led military alliance as aggresive from a Russian perspective is perplexing to say the least. I'm not hand-waving Russian aggression here, just clearly stating a fact that the Russians do not like US influencing bordering nations. Again, this can all be supported by the US lobbying counties to join, only to be vetoed out by other European nations due to the complex nature of Russia and their position in Europe. It's not a simple case of saying that a country joining NATO isn't aggression when it quite clearly is viewed as that because of the tension between Eastern Europe and Western Europe, Russia and Europe along with Russia and the United States.
Who cares if Tajikistan or Belarus is not like Ukraine, if the U.S or NATO see it as aggression why shouldn't Russia have to take that into account? Because it's not a reasonable idea, just like Russia seeing NATO as aggression. Why is Russia special in having the West having to care about their dumb ideas.
China sees most of the South China sea as theirs and would say keeping the status quo is aggression, the rest of the world tells them to fuck off because a country simply seeing something as aggression when it isn't reasonable shouldn't matter to anyone else. China sees Asia as their sphere of influence and would say the U.S/Vietnam/SK/Japan/ Phillipines etc are inflaming tensions. Is China also right?