Do you think it has anything to do with Putin’s ideas regarding Novorussiya?
If you mean Donbass etc. yes in part....why wouldn’t it? But It’s all the other drills and supplying planeloads of military equipment and Nato troops drills which would indicate a threat to Russia - particularly after Nato members refused to address Putins concerns which he raised consistently....
Rather like when Russia was putting heavy armament in Cuba that we wouldn’t stand for and didn’t.