Invading a country unprovoked, launching missiles at schoolgirls is invasion, murder and warcrimes. We don't typically use the word murder for state actors, but letting them use this as a bargaining chip doesn't set a good precedent.
Iran presently also isn't trying to Lebensraum "buffer zones" from other countries lands around itself.
I'm still not sure what this has to do with Iranian aggression?
Only if we ignore all of Iran's proxy warfare.
If we correct your argument so it's actually based on international law, it seems to boil down to "we have to ignore proxy warfare, otherwise Nicaragua might have historically (several decades ago) had a right to attack US military assets." That hardly seems like a reason to deny reality and ignore proxy warfare.