An ironclad bipartisan consensus has formed on the issue: Iran will not be allowed to develop a nuclear weapon. Period. End of discussion. "All options are on the table" to prevent this from happening, George Bush has repeatedly declared, with John McCain singing along. Meanwhile, Barack Obama has hammered home the point even more forcefully: "I will do everything in my power to prevent Iran from obtaining a nuclear weapon, everything in my power to prevent Iran from obtaining a nuclear weapon -- everything."

"Everything" in a president's power includes the largest military machine in human history and the largest nuclear arsenal on earth, so this is not exactly an idle boast. In fact, the American bipartisan political consensus on Iran amounts to precisely this: putting a gun to someone's head and saying, "If you don't do what I want, I'm going to blow your goddamn brains out."

This Bush-McCain-Obama line was underscored this week by one of Obama's top foreign policy advisers, Anthony Lake, who said "the prospect of a nuclear-armed Iran is the biggest threat facing the world," the Financial Times reports.

Think of that: the biggest threat facing the world. Bigger than global climate change. Bigger than poverty and disease. Bigger than growing conflicts over shrinking resources. Bigger than terrorism (which was the last greatest biggest threat facing the world). Bigger than organized crime. Bigger than the Terror War operations in Iraq and Afghanistan and Somalia, which continue to spawn so much death, ruin, extremism and economic turmoil. Bigger than all of these -- and all other threats facing the world -- is the prospect that Iran might, in Lake's words, "get on the edge of developing a nuclear weapon."

This is certainly a remarkable state of affairs, and one which provokes a very simple question: Why? Why is an Iranian bomb (or even the prospect of Iran "getting on the edge" of having one) the ultimate danger facing the world today -- a prospect so dire, so infinitely evil that even the most "progressive" operators in the power structure insist they would be willing to use nuclear weapons to stop it?

Thomas Powers considers this very question in the latest New York Review of Books:

Nothing in the modern affairs of nations has been more exhaustively analyzed and debated than the utility and dangers of nuclear weapons, and yet the dangers posed by Iran with a bomb have been barely discussed. They are treated as a given. The core idea is that Iran cannot be trusted because the country is run by religious fanatics crazy enough to use a bomb if they had one. This is not the first time such arguments have been made. Some Americans, including Air Force generals, believed in the late 1940s that a pre-emptive war against the Soviet Union was justified by the peril of Moscow with a bomb. Twenty years later the Russians, in their turn, were so alarmed by the prospect of Beijing with a bomb that they quietly proposed to the Americans a joint effort to destroy the Chinese nuclear development effort with a pre-emptive attack.

The world's experience with nuclear weapons to date has shown that nuclear powers do not use them, and they seriously threaten to use them only to deter attack. Britain, France, Russia, China, Israel, South Africa, India, Pakistan, and North Korea have all acquired nuclear weapons in spite of international opposition. None has behaved recklessly with its new power. What changes is that nuclear powers have to be treated differently; in particular they cannot be casually threatened....

We must demur slightly from this excellent analysis to note that one nuclear power has in fact used its nuclear weapons: the United States. Back to Powers:

So set aside the question of whether Iran wants an enrichment program to make bomb-grade material or only for the production of electricity... What we ought to ask, then, is why Iran wants its own production capacity for making the stuff of bombs?

What US officials say, when they say anything at all, is that Tehran wants a bomb in order to dominate the Persian Gulf region and to threaten its neighbors, especially Israel. This is a misreading of how other nuclear powers have made use of their weapons. As tools of coercive diplomacy nuclear weapons are almost entirely useless, but they are extremely effective in blocking large-scale or regime-threatening attack. There is no evidence that Iran has a different motive, and plenty of reason for Iran to fear that attack is a real possibility.

Indeed, the Bush administration, far from trying to quiet Iran's fears, makes a point of confirming them every few months. These threats are not limited to words, but are supported with practical steps....

The seriousness of American threats is confirmed by the fact that no significant national leader in the United States has ever disowned or objected to them in clear, vigorous, principled language. It is as if the whole country listens to the administration's threats with breath held, wondering if Bush and Cheney really mean to do as they say, and in effect leaving the decision entirely to them. Americans may count on the President to think twice, but why would leaders in Tehran, responsible for the lives of 70 million citizens, want to depend on President Bush's restraint for their survival and safety? Bush has a history. On his own authority, without the sanction of any international body, he attacked Iraq five years ago and precipitated a bloody chain of events that shows no sign of ending. It would be natural, indeed inevitable, for any government in Tehran, seeing what has happened next door, to ask what could save Iran from a similar fate. An answer is not far to seek: nuclear weapons with a reliable delivery system could do that.

Powers then considers the possibilities of an imminent American strike on Iran:

Bush and Cheney prefer the language of flat command that implies "or else." A long list might be appended here of their frequent warnings that the United States does not trust Iran with the knowledge to enrich bomb-grade uranium and will not tolerate an Iranian bomb. Many of these warnings have been issued in the last month or two and we may expect a continuing barrage until their final days in office. The President's frustration is plainly evident: Saddam Hussein may be gone, but Iran remains defiant, and more powerful than ever. The President's male pride seems to have been aroused; he said he was going to solve the Iranian problem and he doesn't want to back down. The intensity of Bush's desire to crush this final opponent is evident in his words and his body language, but does he retain the power to carry out his threats?

From one point of view the answer seems obvious. It is too late. With the exception only of the neoconservative faithful, every close observer of the American–Iranian standoff says that the administration's threats are empty, that the United States does not have the military resources, or the political support at home, or the agreement of allies abroad, to carry out a full-scale air attack on Iran's nuclear infrastructure, much less to invade and occupy the country. Two of the skeptics, Gates and Mullen, are running the Pentagon, and their cautioning remarks, only a step this side of insubordination, would seem to make attack impossible. But if attack is impossible, why does Bush talk himself into an ever-tighter corner by continuing to issue threats? Does he believe Iran will cave? Are these the only words he thinks people will still listen to? Is he hoping to tie the hands of the next president? Or is he preparing to summon the power of his office to carry out the last option on the table? One hardly knows whether to take the question seriously. It seems alarmist and overexcited even to pose it when the realities are so clear. But it is impossible to be sure—Bush has a history.

Bush indeed has a history. He has a history of launching military aggression. He has a history of launching military aggression on the basis of manufactured threats. He has a history of launching military aggression without the agreement of allies abroad. He has a history of launching military aggression against the advice of "military skeptics," whom he either "retires" or sidelines or ignores when he launches the aggression. He has a history of launching military aggression regardless of the strain it puts on the armed forces or the national treasury.

And he does not need "political support at home" to launch another act of military aggression, if by "political support" Powers means popular backing from the public. Bush is not facing re-election, and never will again. And he has already been given full support from the Democratic-controlled Congress in a series of measures which fully embrace Bush's bellicose stance toward Iran, as well as the specious casus belli he has advanced.

We are indeed simply waiting to see if Bush decides to carry through with his clear intent -- and waiting helplessly, for exactly the reason that Powers outlines: because "no significant national leader in the United States has ever disowned or objected to [the threat of war on Iran] in clear, vigorous, principled language." Indeed, as noted above, all of our "significant national leaders" are in lockstep on this issue, and in their willingness to do "everything in [their] power to prevent Iran from obtaining a nuclear weapon, everything in [their] power to prevent Iran from obtaining a nuclear weapon -- everything."

So yes, Bush has a history of military aggression. And the United States has a history of incinerating civilians with nuclear bombs. What seems to be forgotten in all the bloodlusting furor is that Iran has a history of neither.