If a tactical nuke is used, then it is proof that escalation to nuclear weapons does not imply the global nuclear holocaust that has been acting as a deterrent.

If a tactical nuke is used, then it is proof that escalation to nuclear weapons does not imply the global nuclear holocaust that has been acting as a deterrent. It eliminates the logic of not going to war. Not that "logic" has any connection to "appetite" or that excuses require it.