I still find Threads to be the film with the most effective anti-nuclear messaging. That said, The Day After delivered on providing a grim view into what life may look like after a nuclear exchange.

This movie is still horrifying

This movie is seared into my formative years' memory. Growing up under the threat of nuclear Armageddon has a way of affecting people.

I watched this as a kid, and was forever terrified by the possibility of nuclear war after that. Good movie.