"@ Anony mous -The heavy bombers used over Japan were B17's and B29's, B52's came along much latter"
There's so much wrong with his post...where to begin. The Polaris and Minuteman III currently each contain 3-5 W78 MIRV warheads each with a yield of 335-350 kilotons. Each city hit gets a shotgun effect of 3-5 strikes spaced out around the city.
I don't know where he got the idea that most only contain a 1 kiloton warhead. The only weapon i'm aware of that was so small was the 'Davy Crockett". It was basically a tactical artillery piece to presumably be used against advancing soviet soldiers in the cold war. It was taken out of service in 1971. I'm not claiming they no longer exist just because they were removed from active service,
Yes, the bombs used in Hiroshima and Nagasaki were big and heavy and required bombers. But they got much better at building the things and by the 70's, 3-5 could be carried atop a minuteman missile. Each with 20-25 times the yield of Hiroshima. Here's a pic for scale:
And here is a map showing damage of a 330 kiloton airburst over midtown manhattan. He may be correct that the area completely vaporized may be a few city blocks, but the gray circle shows most residential buildings collapse from Harlem all the way to lower Manhattan. The final orange circle shows 3rd degree burns for anyone caught in the open extending into Brooklyn and New Jersey. Perhaps he has a much more pedantic version of what 'destroying a city' means.. but anyways, this has gone way off subject from the original post.