The US was in no danger of reprisal for the nukes on Hiroshima and Nagasaki... so, in no way could it have been considered a suicide bombing. However, I'm pretty sure that even the most god-bothered mullah in Tehran realises that lobbing a nuke into Israel will result in every major city in Iran being turned into a glass parking lot.

I think it's a lot more likely that Israel will start lobbing rocks, given that currently they're in a similar position to Iran that the US was wrt Japan in 1945.