The world turned upside down for President Bush, Vice President Dick Cheney and the state of Israel on Monday when the National Intelligence Council, drawing conclusions from new information after a year of internal debate about Iran's nuclear weapons program, said that, in fact, there was no problem after all -- and that "in fall 2003, Tehran halted its nuclear weapons program."

With those nine much-argued words, the American intelligence community abruptly cut the ground from beneath years of threats to bomb or invade Iran if it did not do what the NIC concluded "with high confidence" that it had already done. In the pained bleat of denial that predictably followed from the White House and its allies, a basic question got pushed to the back of the line: Who pressed to declassify these highly inconvenient findings?

Intelligence stories rarely get more complicated than this one. But this much is clear: Bush is the nation's chief classification officer; he can make and unmake secrets at will. The White House says the president was briefed on the findings in the nearly 140-page report on Nov. 29, but the chief subject of that meeting was probably the question of declassification -- whether to send the secret National Intelligence Estimate with its explosive first sentence to Congress and let it emerge in a slow agony of leaks over a matter of days or weeks, or to cauterize the wound and declassify the key judgments at the outset, hoping the argument would quickly burn itself out?

One of the basic laws of intelligence is that no big secret can be kept that can be written on the back of an envelope. No matter who first suggested declassification, it was the president who ultimately decided to release the nine words that reversed the conclusion of a previous intelligence assessment on Iran's bomb program in 2005, and he did it because it was going to come out anyway.

One thing we know, from the document and from the fact of its declassification, is that reform of the intelligence community has apparently worked. The creation of Mike McConnell's job as director of national intelligence has successfully insulated the CIA from pressure by the White House of the sort that played such a big role in the Iraq WMD fiasco. To call the new NIE "inconvenient" is simply another way of saying that it is not politicized. It is free from influence by policymakers. It represents the honest conclusion of the analysts given the job of deciding whether Tehran was trying to build a bomb. The fact that the NIE says what it says, and its release, both show that the White House has lost control over American intelligence. This good news probably needs a lot of hedging and qualification, but it is good all the same.

Even more important than the reason we know about the intelligence estimate is the immediate practical significance of the finding itself. Confronting the threat posed by the existence of an Iranian nuclear program has been at the core of Bush's not-yet-quite-100%-dead effort to change the political landscape of the Middle East. "Tehran halted its nuclear weapons program" is a tough obstacle for the president to get around. His quick response -- "Iran is dangerous" -- has been echoed by Israeli Defense Minister Ehud Barak and by Cheney's many supporters.

All argue that the bomb-design program dropped in 2003 was the easy part of building a bomb. The hard part -- the reason why so many countries that might like a bomb don't have one -- is the immense effort required to manufacture fissionable material, which is exactly what Iran is doing with its ongoing centrifuge program to enrich natural uranium. The NIE skeptics argue that Iran or any other country with the ability to make fissionable material could crank up a bomb design and development effort in a hurry -- not in five minutes, perhaps, but it wouldn't take a decade either.

Nuclear weapons are a potential threat to everyone within their range, but an Iranian bomb has always been seen as extra threatening by Israel. In its lurid form, the Israeli fear was of nuclear weapons as the instrument by which Iranian President Mahmoud Ahmadinejad would make good on his threat to wipe Israel off the map. But the danger of that is actually low, maybe even zero, for the very good reason that no country would use nukes against an enemy that also had nukes, for fear of retaliation in kind. The Israelis sometimes argue that the Iranians are crazy and might do it anyway, but that argument is mainly for public effect. Israeli discussion of this matter, read carefully, strongly suggests a different source of Israeli concern -- the painful prospect of "losing" the country's own nuclear weapons. Not the physical weapons but the implicit threat to use them if pushed to the wall. Loss of this ultimate threat would not require surrender but something in the Israeli context perhaps as difficult and painful -- compromise.

At this point in the discussion, 20 or 30 pages of explication might usefully be inserted; for the moment, one factor is paramount -- Israel dreads the difficulties of every sort promised by an Iranian bomb and has been hoping that the Bush administration was going to shut down the possibility once and for all. The new NIE intelligence estimate kills that hope.

What the NIE skeptics say about bomb development -- and the continuing dangers of uranium enrichment by Iran -- is true, and it is the reason that Iranian nuclear activity will be subject to international pressure for a long time to come. But the NIE neverthelessundercuts arguments for war -- not war at some theoretical future date but war soon, even war now, while Bush remains in office and in command of the U.S. military. The conclusion of American intelligence that there is no Iranian bomb program makes it impossible to rally support for a new war from the American people, already sick of Iraq, or from Congress, still smarting from its folly in giving the OK on Iraq, or from almost every other country in the world, which never believed that the invasion of Iraq made sense to begin with.

Talk of war with Iran from the administration, and especially from the office of the vice president, has been a recurring theme of the Bush presidency. But over the last year it has grown increasingly difficult to imagine the U.S. taking on all the uncertainty of a third war in the Middle East when the first two have stretched the military to its limits. But now, even the threat has become impossible. Who would believe it? Who would permit it?

Fear of Iraqi weapons of mass destruction was Bush's explanation for invading in 2003, but it is likely that his real target was something else -- the defiant government of Saddam Hussein. Threats against Iran were cranked up soon after the fall of Baghdad, and the target was similar -- the defiant government in Tehran, with fear of a bomb the familiar rationale.

It is an irony that Iran's nuclear program was both more serious and more advanced than Iraq's, but it is not irony that pushes the affairs of the world. The political landscape we see in the Middle East is the one Bush will leave behind when he returns to Texas, and the picture from his point of view is a bleak one. Absent a big surprise or sudden turn in the road, the president's attempt to remake the Middle East leaves an Iraq with a Shiite government in friendly concert with a Shiite Iran whose leader speaks with a new confidence as he brushes aside American threats not to "allow" or not to "tolerate" -- words used by Cheney and Bush -- a bomb program, which American intelligence says was abandoned four years ago.

Thomas Powers is the author of "The Man Who Kept the Secrets: Richard Helms and the CIA" and "Heisenberg's War: The Secret History of the German Bomb," among other books. He writes frequently for the New York Review of Books.