As written in https://news.ycombinator.com/item?id=24522125 I don't believe everyone apparently having more offensive than defensive capability is necessarily the most stable of situations.
[1] the true end: https://www.youtube.com/watch?v=cIpTE-aHEZ0
On the "mineshaft gap": https://news.ycombinator.com/item?id=23712008
Have you got change for 20 million people? https://boardgamegeek.com/boardgame/713/nuclear-war
[2] "There was too much there to move, and we knew we had to break [Chrome], burn her straight down, or she might come after us."