Threads (1984) via https://youtu.be/5Srqyd8B9gE
And if you want to know how the world would like after the movie Threads, read the following book:
A Canticle for Leibowitz (1959) via https://en.wikipedia.org/wiki/A_Canticle_for_Leibowitz
Video unavailable (in Australia at least)
Also, this section of "In comments", among others, applies to your comment: "Please don't complain that a submission is inappropriate. If a story is spam or off-topic, flag it."
It's true that in order to also fill that gap in your mind it must be plausible to you too. I don't know if it helps to know this comes from an organisation of experts whose job it is to think about this kind of thing all the time. In any case, I think this kind of speculation is necessary in order for the news we have seen about nuclear threats to have any meaning. Otherwise, it's a bit like hearing that Russia would like to crash the moon into Europe. Ok perhaps, but how could that be done? This article attempts to give an answer.
[1] https://www.bbc.co.uk/news/world-europe-60547473
[2] https://news.sky.com/story/russian-diplomat-if-nato-threaten...
[3] https://www.nytimes.com/2022/03/02/opinion/ukraine-putin-nuc...