Yeah, the precise definition of MAD and the other policy options that result in the strategy I described are probably wrong. So what? The point is that it is policy as far as I know that any nuclear attack or specific threat to make one is to be responded to by a full-scale nuclear counterattack, regardless of how big or small the attacking country's arsenal is or what we think of their leadership. This is place for the purpose of deterring any attack, including by small countries. If it happens and we fail to follow through, then the deterrent is weakened, and the thinking of other nations about the viability of a first strike may change.