Right, there's plenty more creative ways to kill a civilization besides nukes. Use some imagination. Here's a random scenario I just made up: Imagine that there was, like, One de facto world government, and imagine that a cartoonishly evil hostile nation to that giant superpower managed to snake its way into that other nations' medias, while indirectly controlling a chunk of its government through a series of middlemen, exploiting impending economic crisis resulting from generational age gaps and giant ponzi schemes-- marketted as social welfare-- doomed to crash in the coming decades. Now imagine discouraging people from saving by devaluing the global currency as a means of regressive taxation against the poor, all while leeching absurd amounts of wealth from the single wealthiest nation in the form of global trade controls designed to shift costs out of your own economy. And then let's imagine that instead of this culminating into a catastrophic doomsday-like economic event but instead just enough slowdown is created for that single cartoonishly evil mustache cigar smoking concentration camp nation to gain global dominance while most media has everyone's attention diverted towards an irrelevant power that can barely keep a battallion of tanks tracked long enough for a 10 mile push.