From a 1965 episode - Smart and 99 are looking at a picture of a mushroom cloud:
99: Oh, Max what a terrible weapon of destruction.
Smart: Yes. You know, China, Russia, and France should outlaw all nuclear weapons. We should insist upon it.
99: What if they don't, Max?
Smart: Then we may have to blast them. That's the only way to keep peace in the world.