I've been out of the intelligence business for many years now, so I've stayed out of the debate over Iran's nuclear program.  I learned a long time ago that when people who don't have access to highly classified intelligence about an issue like this one prattle on about what they think is happening, or is likely to happen, they tend to get it wrong.  But the debate over Iran's nuclear program has become so feckless -- so disconnected from reality -- that perhaps it's time to inject a dose of what those of us who served on the national security side of the Reagan administration used to call "real-world intelligence." 

Let's focus on the three big questions that lie at the core of this potentially literally explosive issue:

When, precisely, will Iran have a nuclear weapon?

In the real world of intelligence, you never get a report from a spy saying, "This country will have a nuclear bomb two weeks from Thursday."  It just doesn't work that way.  By the time a spy tells you there's a nuclear weapon at the military base here, or hidden in the warehouse with the green roof at the end of the dirt road there -- that country has had a nuclear bomb for years.

To estimate when a country will have a nuclear bomb, you work with ranges, estimates, and projections based on evidence and experience.  And when you look at Iran through this prism, here's what you'll see:

It was the United States that invented the nuclear bomb, of course, in World War II.  The total elapsed time from launching the Manhattan Project to Hiroshima was six years.  And that was back in the 1940s, well before computers were widely available.  There's no need for Iran to re-invent the bomb; they can download the plans.  Or they can ask any grad student at MIT or Cal Tech how to build a nuclear bomb.  Buying the necessary parts is difficult, and expensive, but these parts are available on the black market to any country, or any group of terrorists, with the will and the cash.  The really hard part is creating the nuclear fuel, for instance by converting uranium ore into enriched U-235, or plutonium-239.  But it can be done by any country that has the scientific and mathematical talent, and the money.  Indeed, quite a few countries have already done it.  Iran is Persia; they've got the scientific and mathematical talent, and oil exports have provided more than enough money.  And they've been working at it for several years now.

Moreover, there are some kinds of projects where predicting the precise length of time required for completion is easy, and other kinds of projects where it's not so easy.  The pilot of a jumbo jet en route from Chicago to London knows to the minute when he'll land at Heathrow.  A skilled carpenter can tell you how many hours he'll need to build your new deck.  But if you ask an experienced author when he'll complete the manuscript of the book he's writing, he'll just shake his head.  Sometimes you cannot meet the publisher's deadline no matter how hard you work, and other times you find yourself whizzing through the pages and sending off the finished manuscript weeks before it's due.  You just never know how long it's going to take, and if your estimate turns out to be accurate, it was less a brilliant prediction than a lucky guess.

It's the same with building a nuclear bomb.  One time the experts will estimate that a particular country is, say, two to three years from actually having the bomb.  Five years later, that country still hasn't got its bomb, and the experts who haven't already retired just shrug and say they did their best with the evidence at hand.  Another time, at a top-secret meeting of the Ad-Hoc Crisis Committee, the experts assure you there's at least a two-to-three-year window before any nuclear showdown with a certain country.  So you take the experts out to lunch to thank them for their help in defusing what looked to be an imminent confrontation.  Then you stroll back to your office and find the place in total panic because that country set off an underground nuclear blast while you and the experts were dawdling over coffee and mousse au chocolat.

Simply put, Iran is "there" -- which means either they already have the bomb, or they'll have it in six weeks, ten months, next year, or the year after that.  You cannot be more precise, so don't believe any Washington spin artist who suggests oh-so-confidently that we'll know when Iran is, say, five months, three days, and nine hours from having the bomb.  No, we won't.

If Iran is on the verge of having a nuclear bomb, why do I keep hearing that the CIA isn't convinced Iran has even made the decision to use its nuclear program to build a weapon?

It's unfortunate, but in the real world, our intelligence service sometimes plays politics.  It isn't our spies who do this -- they're among the finest, most talented and dedicated people I've ever had the privilege to know -- but the analysts.  If they believe a certain intelligence judgment will trigger action they oppose -- for instance, a hardline political stance or even a military attack -- they'll refuse to reach that judgment no matter how strong may be the evidence.

During the Reagan years, when a lot of senior intelligence analysts believed that détente was a better approach to dealing with the Soviet Union than confrontation, getting the CIA to acknowledge that the Kremlin was sponsoring terrorism and actively supporting armed insurgencies around the world was like pulling teeth.  They just didn't want to give President Reagan the ammunition that proved that what he kept saying about the Russians was absolutely correct.  They were afraid of what he'd do with that ammunition.  (And part of my job was precisely this: to extract from inside the CIA the evidence that was there, pull it together into a judgment about what this evidence meant would likely happen, and then get that judgment to the president.)

I realize that it's disturbing to read that this kind of gamesmanship takes place at the upper levels of our intelligence service.  But it does, and as the debate over Iran comes to a boil, it's crucial to understand how the game gets played.  So here's a non-political little anecdote just to illustrate what it's like when someone gathers the evidence, but obstinately refuses to turn that evidence into a judgment because he opposes the likely consequences:

On Wednesday, word reaches me the editor of this website is planning to host a barbecue on Saturday evening for his favorite contributors.  But he hasn't invited me, and I'm furious.  I want to be at that barbecue, and if I'm not invited, I'm going to show up anyway and cause a big stink.  So I order my intelligence service -- my wife and kids, who think that getting into a fight with my editor would be idiotic -- to hop on a plane to the city where my editor lives, keep an eye on things, and let me know what's up.

On Thursday, they call in to report the've just spotted my editor emerging from a Walmart with two cases of beer and a bag of charcoal briquets.

"What do you think's going on?" I ask.

"We can't say for sure," my wife replies blandly, "but we'll keep a close eye on things and get back to you with any new developments."

On Friday morning they telephone again, this time to report they've just spotted the editor's wife in the supermarket buying hamburger meat, hot dogs, several bags of potato chips, and a bucket of coleslaw.  And in the afternoon they call yet again, reporting that five of this website's top contributors have landed at the local airport and checked into hotels near my editor's home.

"What exactly does all this mean?" I ask, perhaps a bit less calmly than before.  I can hear my wife taking a deep breath before she replies.

"Well, we can say with a high degree of confidence that your editor is taking steps that are consistent with one day hosting a barbecue for his favorite contributors.  But at this point in time," she adds, while my kids start giggling in the background, "we have no evidence that a decision to hold that barbecue has actually been made."

By the time they call me a fourth time, at 6pm on Saturday, to report that my editor has lit the grill and that a line of taxis is snaking up his driveway, it's too late for me to get there and start a fight.  The editor's barbecue will take place without me, and I must learn to live with that.

Of course Iran is building a nuclear bomb; the evidence is obvious and overwhelming.  The only purpose of those leaked National Intelligence Estimates asserting that Iran hasn't actually made the decision to build a nuclear bomb, and of similar leaked documents from European intelligence services, is to prevent what the analysts fear would happen.  They're afraid that if they officially judge Iran to be on the verge of having a nuclear bomb, political pressure for a military attack will become irresistible.  They want to delay action until it's too late, so we will be left with no choice except to live with a nuclear-armed Iran.

Will the Israelis launch a military strike against Iran?

There are two great lessons of the 20^th century:

The first great lesson is that crazy people sometimes get political power.  Hitler was crazy.  He was brilliant, cunning, deeply insightful -- and a raving lunatic.  So was Uganda's Idi Amin, and so were the maniacs in Cambodia who slaughtered two million of their own people, including everyone they could find wearing eyeglasses on the bizarre theory that anyone who had poor eyesight probably had ruined their eyesight by reading too much, and therefore was an intellectual.  (Actually, when you study history, it's astonishing how often crazy people get political power.)

The second great lesson is that when crazy people with political power tell you what they're going to do -- believe them.  They're not kidding.

And of all the people who've learned these lessons, it's the Israelis.  Study the history of Nazi Germany, and you'll discover there were quite a few Jews who could have gotten out safely in 1936, 1937, and even into 1938.  But they decided to stay.  Some of these Jews who chose to remain in Germany were professionals -- for instance, physicians and architects.  Others owned businesses such as department stores and factories.  They had beautiful homes, good lines of credit with their bankers in Frankfurt and Zurich, perhaps season tickets to the Berlin Philharmonic.  They would meet, talk, and assure one another that things really weren't as bleak as they seemed:  "Look, these Nazis are distasteful and maybe a bit nuts.  But what are they going to do?  Kill us all?"  As a matter of fact -- yes, that is precisely what the Nazis did.  Even worse, Hitler and his murderous gang of Nazis made no secret of what they had in store for the Jews.  Indeed, they never shut up about what they had in mind.  But what they said they planned to do was so horrific, so utterly beyond rational imagination, that too many Jews simply didn't believe them until it was too late to escape.

Iran's leaders, like the Nazis before them, are a bunch of genocidal lunatics.  They are the world's leading sponsors of terrorism, they slaughter their own people every day, and in just the last month they've described Israel as a "cancerous tumor" that needs to be wiped out, while asserting that Israel's very existence is "an insult to all humanity."

The Jewish people won't make the same mistake a second time.  They won't wait patiently for Iran to get its hands on a nuclear bomb and then annihilate another six million of them.

I have no idea precisely how the Israelis will act against Iran, or when they'll do it.  In just the last two weeks, diplomatic relations between the White House and Israel have gone from testy to downright nasty; if news reports from Jerusalem are accurate, there was quite a blow-up at a recent meeting between our country's ambassador to Israel and Prime Minister Benjamin Netanyahu.  And the chairman of the U.S. Joint Chiefs of Staff, General Martin Dempsey, has lately said some things about U.S. military cooperation with Israel that suggest that relations between our armed forces and theirs are somewhere between chilly and frigid.

My guess is that Israel would prefer to hold off on any military strike as long as possible; there's always a chance that Iran's own people will rise up and overthrow their government.  Certainly the Israelis would prefer to delay any action until after the U.S. elections in November.  They would get a lot more sympathy, and practical military support, from a President Romney than from President Obama.  But if Iran's nuclear bomb program crosses whatever the Israelis have judged to be a "red line" before November, they will have no choice but to launch an attack immediately.

There's one other scenario that's unlikely, but possible: think back to the 2008 election.  It was all going to be about the war, which is why John McCain was the GOP candidate.  But in late September, Wall Street melted down, and by election day Americans were concerned not about about the war, but about the economy.  And -- alas -- war-hero McCain had nothing impressive to say about that.  This time, if political polls in early October show the president far behind Romney in key swing states like Ohio and especially Florida, a desperate President Obama may try to turn things around by doing what only a president can do.  He could order an attack on Iran, or co-ordinate an attack with Israel.  The election suddenly would be about the war, and the president's spin-artists would try to make the November 6 vote a referendum pitting a businessman and his budget-geek running mate against the commander-in-chief who killed bin Laden and took out Iran's nukes.

One way or the other, don't be surprised if one morning in the not-too-distant future you turn on your television and see smoke pouring from what used to be Iran's nuclear bomb factories.

Herbert E. Meyer served during the Reagan administration as special assistant to the director of Central Intelligence and vice chairman of the CIA's National Intelligence Council.  He is author of How to Analyze Information and The Cure for Poverty.