Earlier quoted context omitted.
It looks like you are using salami tactics. Salami tactics works in both ways. You say that nobody will went crazy when a tactic nuke will be used against RF army. Right? Can you draw the line, please? When this war between two nuclear states will be nuclear, if even use of tactical nuke is not enough for you?
Ukraine isn't a nuclear state. They destroyed their nukes and joined the non-proliferation treaty in 1994.
[1]Budapest Memorandum was not fulfilled, so Ukraine regain their status of nuclear state.