Look at a picture of Tokyo after it was firebombed.
http://articles.chicagotribune.com/1995-03-09/news/9503110030_1_civilian-deaths-firebombing-raid
TOKYO — Retired Air Force Gen. Earl Johnson has no regrets about the mission he completed 50 years ago Thursday-the firebombing of Tokyo that caused 100,000 civilian deaths.
U.S. no more dangerous than Iran? This is probably one reason why people try to say "we blame America". You're equating the risk of the U.S. having nuclear weapons to the Iranian regime. No one knows exactly what Iran would do, but it's likely they'd use nuclear capability as a way to bully others in the region and be defiant. At the same time, this destabilizes the region, since other Arab nations will want to pursue nuclear weapons to counter the Iranian threat.