Japan didn't need the internet to know they'd been hit by the most dangerous weapon the world had ever seen. The sun rose twice.
And I don't need to justify this. The decisions were made 75 years ago by people who are all dead now, and a generation before I was born. We have the benefit of hindsight now, and the world's changed. My original statement even laments the fact that the bombs were dropped due to tragic inability to understand or communicate. Half or more of the people here have been saying "if we knew then what we know now, we wouldn't have" and that's great. Doesn't apply to the original issue, back in 1945, when the Americans had no good answers left, and picked what seemed like the least bad one -- incinerating two cities full of civilians, to send the message "give up" in the largest letters the human race has ever seen.
I'd like to think we've learned the lesson as a species. These weapons have never been used in war since. Hopefully, we have. I hope to never learn I'm wrong.