Simple, and not stated. WW1/2 Were, and WW3 might yet be, fought over the end of

Simple, and not stated.
WW1/2 Were, and WW3 might yet be, fought over the end of agrarian empires and the evolution of the age of industrial nation states. Under this post-imperial order, the necessity of alliances to protect sovereign nation states from empires that would deny that sovereignty is the principle purpose and method of the transition.