Normally, if we show up at the flagpole at noon to confront each other, and you throw a punch, you have escalated things to a fistfight, and then my return punch is not an escalation. If I pull a knife, I have escalated things to a knife fight. We escalate from fist to knife to gun. Reciprocation - self defense - does not count.
The only way to torture the term into contextual use is to suggest that Russia is not firing rockets at NATO because Ukraine is not NATO, but NATO is firing rockets at Russia because all these missile systems are not Ukrainian, but NATO. This is Putin's framing, and it incorporates the idea that the missile systems are actually being manned but US & EU soldiers.
If you are not adopting that frame, "escalation" only really works if you explicitly define the context as a Great Powers proxy war with a potential nuclear endpoint, where Ukraine is stipulated for the sake of argument to have no agency.