Which nations in your opinion would be the instigators of any third world war?

If indeed any such scenario were ever to come into fruition. It could be that the much vaunted war on terror could escelate into such an outcome. Or the Chinese could flex their military muscle leading to catastrophic repercussions. Will, in your opinion, the long threatened & dreaded 3rd world war actually ever happen. Let’s hope not, ever the optimist.