It has been clear for two decades now that an all-out nuclear war would eliminate the major breadbaskets of the world for up to half a century. The Temperate Zones would become essentially uninhabitable. Any US "Government" would have to relocate to coastal Mexico or Central America. Russia would also be depopulated. China's and India's populations would fall through the floor. Forget Europe.
So maybe we should takes steps to ensure this never happens, just maybe, no?