I personally feel that most hostile regimes to Israel are all talk. Realistically, they know that they do not stand a chance in a conventional fight, and as stupid as Ahmedinejad appears to be, they real power behind him, Khameini, is not. I am sure that Khameini is well aware of Israel's capabiliities and wou do everythig to avoid a showdown.
Red Cross delivers aid to Taiz, Yemen, for first time since August (Reuters)
from the article: Iran military head warns of 'heavy damage' should Israel attack