Will Iran launch a nuclear attack on Israel or the US unless their nuclear program is stopped?

The question really is, what is their long-term goal here? It is not nuclear Armageddon, to destroy the West as many foresee, perhaps starting with Israel and the United States using long-range missiles with nuclear warheads. The answer here is no. They are belligerent but they are not crazy. They are portrayed as reckless, bloodthirsty, and willing to do anything to kill their enemies, even at their own peril because of their ideological zeal fueled by religious fervor and bigotry. That, indeed, is their mindset but they are not uniformly suicidal. They welcome suicide missions amongst their following but do not want to throw their country away, simply to have a gesture in doing their worst when it is not likely to succeed, and they would end up the biggest losers.