Nuclear threat never really went away, we just don't have the emotional capacity to seriously think about it for too long. I could recommend relevant podcast episodes by Sam Harris.

Now that it's on everyone's minds, I hope it will not be quickly forgotten in the aftermath.

Edit: if you need an immediate calming down… Even a crazy dictator is unlikely to want to destroy the world, because then there would be no one to rule over. Simplistic, but slightly reassuring.