I don't mind fielding this one....as it comes from a person capable of rational discourse, and not someone who on thread after thread seeks to promote extreme right wing/Marxist values.
First off, i think that their has never been a truly valid reason to even consider using weapons of such destructive capabilities, however, we all do exist in a heavily factional world in which they do exist....on several sides of existing alliances, treaty organizations and 'wild card''rouge status' sovereign states.
It is one of the greatest benefits of a coalition in that no one single nation need to feel the weight of such a threat without the backing of fellow alliance nations to back its right to self protection for its peoples and its future.
I do respect a nations right to self defense, but only with an agreement with its coalition partners in matters that involve nuclear weapons...and that is only acceptable in the world we currently live in.
In a more perfectly developed world, i believe a system will be created that will pinpoint and destroy any aggressor nation with an autonomic and irrevocable devastation for its choice to launch attacks on its neighbors...thus the annihilation of an aggressor falls upon itself as a choice for its own actions.
I also think that if such a system could be implemented, it such be capable of firing a single 'warning shot' across the 'bow' of any nation threatening {as you described it} any such aggression before the final mandated penalty is implemented.
I'm convinced that's mankind's only possible choice to survive the future irrespective of the holocaust that we are currently wreaking on the planet in a non military fashion.
Of course in an idealistic vision of the future, their will be no borders and complete homogeneity of humanity with no more reasons for petty squabbles....that sounds pretty bleak too.