In Israel it seems that the intelligence services still feel able to tell it like it is. I am not sure the same can be said for the U.S. and no doubt other countries as well. The chief of Mossad, Tamir Pardo told a meeting of Israeli ambassadors that Iran's having nuclear weapons would not be an existential threat to Israel.
Whatever the irrationalities of Iranian foreign policy Iran's government is rational enough to know that any use of atomic weapons against Israel would result in being wiped out by the response from both Israel and other countries such as the U.S. Even the Revolutionary Guard would not want to play suicide jihadists. They are too busy amassing wealth from ownership of business enterprises.
Pardo said that talk of an existential threat is being used too loosely. The phrase is used by many hawks both in Israel and the U.S. often to promote an attack on Iran.
Pardo is just the latest intelligence official to warn against a pro-war stance against Iran. Meir Dagan Pardo's predecessor cautioned the Israeli government against attacking Iran.
Dagan claimed that any attack on Iran could spark a dangerous regional war.
Dagan said that Hezbollah and Hamas could respond with massive rocket attacks on Israel. His comments infuriated many Israeli politicians. For more see this article and also here. Iran has all along claimed that it is simply developing nuclear power facilities not a nuclear bomb.