The principle is beyond the Nuclear policy. It's a famous winning strategy in game theory called "tit for tat" which can be considered as the foundation of all moral principles of human society.
https://www.edge.org/conversation/william_h_press-freeman_dy...
https://en.wikipedia.org/wiki/John_von_Neumann#Mutual_assure...
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As a note, I can't find a date for Von Neumann coining the MAD term. It seems likely to me that it would predate Nash's work, though as I said earlier, the existence of such equilibria was already well known (It was jut not proven that for large classes of non-zero-sum games there must exist at least one such equilibrium, which was Nash's contribution).