The most interesting point in the new National Intelligence Estimate, which reports that Iran halted its nuclear weapons program four years ago, is not about what Iran did or did not do in developing nuclear weapons. It is about how Iran makes decisions about such things.

The U.S. intelligence community does not believe Iran is a madman.

"Our assessment that Iran halted the program in 2003 primarily in response to international pressure indicates Tehran's decisions are guided by a cost-benefit approach rather than a rush to a weapon irrespective of the political economic and military costs," says the NIE. "This, in turn, suggests that some combination of threats of intensified international scrutiny and pressures, along with opportunities for Iran to achieve its security, prestige and goals for regional influence in other ways, might -- if perceived by Iran's leaders as credible -- prompt Tehran to extend the current halt to its nuclear weapons program."

Whether American politicians accept or reject the assumption that Iran acts rationally will have tremendous consequences for the fate of the Middle East and for our security.

The case for believing that Iran is an irrational actor largely rests on the shoulders of its current president, Mahmoud Ahmadinejad. This is because Ahmadinejad routinely says irrational things, especially when it comes to Israel.

In 2005, Ahmadinejad convened a conference called "The World Without Zionism." Here, he laid out an Apocalyptic vision in which Israel -- or the "Zionist regime," as he invariably calls it -- becomes the final battleground in a long struggle between Islam and the West.

"The establishment of the Zionist regime was a move by the world oppressor against the Islamic world," he said. "The skirmishes in the occupied land are part of the war of destiny. The outcomes of hundreds of years of war will be defined in Palestinian land."

"Israel must be wiped off the map," Ahmadinejad said.

A Congressional Research Service report published in August referenced reports that contend "Ahmadinejad believes his mission is to prepare for the return of the 12th 'Hidden' Imam, whose return from occultation would, according to Twelver Shiite doctrine, be accompanied by the establishment of Islam as the global religion."

"I have a connection to God," Ahmadinejad said at a Tehran mosque last October. He added that President Bush "also receives inspiration -- but from Satan."

All this inevitably suggests a chain of thought: A leader who believes it is his job to usher in an Apocalyptic age, where Israel is destroyed and Islam becomes the global religion, cannot be deterred from constructing, or using, a nuclear weapon. Therefore, an Ahmadinejad-led Iran must be pre-empted from obtaining one.

This chain of thought draws us toward another pre-emptive Middle Eastern war and counsels that we risk all the horrendous unintended consequences that could flow from such a war.

But is Ahmadinejad really Iran's decider? If he had personally driven Iran's nuclear-weapons policy, the NIE released this week would make no sense. Admadinejad was elected president of Iran on June 24, 2005. The NIE says Iran halted its nuclear-weapons program in the fall of 2003 and had not restarted it by the middle of this year. During the whole time Ahmadinejad has been president, in other words, Iran's nuclear-weapons program has been halted.

Apparently, the madman did not call the shots.

His predecessor, Mohammad Khatemi, could have warned him of that. Khatemi, a moderate "reformer" (by Iranian standards) was elected and re-elected Iran's president by super-majorities of the popular vote. For four of his eight years in office, his supporters controlled a super-majority in parliament. They never enacted their reform agenda, however, because it was vetoed by the Council of Guardians, which is comprised of six clergymen appointed by Supreme Leader Ayatollah Khamenei and six secular lawyers appointed by the Iranian judiciary.

"In January 2007," the Congressional Research Service reported, "an Iranian newspaper owned by Khamenei admonished Ahmadinejad to remove himself from the nuclear issue."

The intelligence community assumes a certain long-term stability among Iran's real deciders. "This Estimate does assume that the strategic goals and basic structure of Iran's senior leadership and government will remain similar to those that have endured since the death of Ayatollah Khomeini in 1989," says the NIE.

President Bush seems to agree. "The NIE talks about how a carrot-and-stick approach can work," said Bush at his Tuesday press conference. "And it was working until Ahmadinejad came in. And our hope is that the Iranians will get diplomacy back on track."

Bush's bet is simply this: The ayatollahs may be immoderate, but they are not irrational.