For most of my three-decade career handling national security budgets in Congress, Iran was two or three years away from obtaining a nuclear weapon. The idea of an Islamic bomb exerts a peculiar fascination on American political culture and shines a searchlight on how the gross dysfunctionality of American politics emerges synergistically from the individual dysfunctions of its component parts: the military-industrial complex; oil addiction; the power of foreign-based lobbies; the apocalyptic fixation on the holy land by millions of fundamentalist Americans; US elected officials' neurotic need to show toughness, especially in an election year. The rational calculus of nuclear deterrence, which had guided US policy during the cold war, and which the US government still applies to plainly despotic and bellicose nuclear states like North Korea, has gone out the window with respect to Iran.
You can read the rest here.
Also from Peter Beinart, an argument I don't have the same personal standing to make, about the potential for American Jewry to help spare Israel a rash error:
Yes, Iran's acquisition of a nuclear weapon would create a lot of dangers and complications. But according to the latest testimony from the most authoritative American intelligence expert, the U.S. is not sure that Iran is even trying to build a bomb. It says nothing good about our current political/strategic climate that there is so much loose talk about "preventive" war at this stage. Eisenhower would not have talked this way, or Rabin, or other strong leaders from those two countries' modern history.