The only deterant to any nation that has or may obtain a nuclear weapons to prevent them from using it is an absolute guarentee that they will face an all out nuclear retalliation. That is the only means we have of preventing a nuclear war. As I mentioned earlier even if the United States used a nuclear weapon in an attack against another nation it should face a full retallitory nuclear attack by other nuclear weapons nations. Only the threat of nuclear anniliation of a nation will prevent a nation from using nuclear weapons.
And no, Iranian President Mahmoud Ahmadinejad has never threatened an Iranian attack against either Israel or the United States. Iran is unable to even attack the United States or Israel in any significant manner and, while Ahmadinejad has repeatedly called for the end of the "zionist controlled" State of Israel he has also stated that this will happen internally in Palestine without any direct actions by Iran. President Mahmoud Ahmadinejad opposes the violations of the Rights of the Palestinians by the "zionists" in Israel and has called repeatedly for a general election of all voters in Palestine to establish a government (i.e. a one-state solution) in a democratic process. He has also stated that if the People of Palestine, including the Jews, decide through a democratic process that a two state solution is the final answer that he and Iran would support that decision.
Iran would never use a nuclear weapon as it would face a nuclear retalliation just as Israel or any other nations should face nuclear retalliation if they use a nuclear weapon. The same identical criteria must be applied to all nations.
There is a real simply issue that must be addressed. Those nations that are authorized to have nuclear weapons under the NPT need to greatly reduce their nuclear arsenals. They are doing that. Nations that have nuclear weapons in violation of the NPT need to dismantle those weapons. Nations that do not have nuclear weapons should not build nuclear weapons. That is exactly what the NPT states.
Today Iran has no nuclear weapons and we don't even have evidence that Iran is actually trying to build a nuclear weapon. It is purely speculative. We know Israel, Pakistan, India and N Korea have nuclear weapons in violation of the NPT and the entire UN should be taking all actions necessary to disarm these rogue nuclear weapons nations. If we can impose economic sanctions on Iran for just the speculation that Iran might be attempting to build a nuclear weapons, which we have done, then even greater economic sanctions need to be imposed on those nations that we know have nuclear weapons.