They could use a Claire Chennault and the AVG type set up. Certainly, Putin would declare that an act of US aggression even though he has a long track record of using his own mercs for (not so) plausible deniability.
Putin will dub just about anything he doesn’t like an “act of US aggression”. He uses that like “that’s racist” like a lib.
Did you read all of his declaration of war closely? It is hard to read the translation but it is a rant of someone fed up with being the weak man in the world compared to what the Soviets once were. Never saw a little man with power that did not have a Napoleon complex. He has lost his marbles this time and acting out his frustration.
The Politburo better take him out if they know what is good for them. He has made himself popular with the people but I wonder how popular he can be when they are locked out of the world?
In a bunker in the Urals. It is a good place to die.