Don't believe what you read about Iran's nuclear program. We know as much about it as we did about Saddam's weapons of mass destruction. Iran could test a nuke next week, or not for another 20 years. It all depends on who you want to believe.
The Israelis imply that Iran is a few turns of a screwdriver away from completing its nuke. Britain says Tehran has been working hard on a design "since late 2004 or early 2005" and is "close" to having a bomb. The U.S., in a 2007 National Intelligence Estimate, says Iran stopped working on a bomb in 2003 but could restart that work at any time. The Iranians, of course, say they're not working on one at all. The International Atomic Energy Agency (IAEA), which inspects Iran's nuclear facilities, says it has found no evidence of a bomb program but sees grounds for suspicion as to Iran's ultimate intent.
One reason the estimates are all over the canvas is that Iran, like Iraq, is one of the world's worst countries in which to establish facts. It's a vicious police state dedicated to stopping its national-security secrets from leaking. The few journalists and academics allowed into Iran are sharply circumscribed in their contacts and the places they can visit. The quickest way to be arrested or escorted out of that country is to ask questions about its bomb. Western diplomats and intelligence operatives have only marginally better access. The IAEA knowledge of Iran's nuclear programs is limited to what Iran wants to let it know although it keeps a close eye on Iran's main enrichment plant at Natanz, it had no idea until a week ago that a second plant was under construction. And that may not be the only secret facility.
Another reason for the different estimates is that Iran has multiple nuclear programs. We are likely to find out that the nuclear facility revealed recently near Qum is under the control of the Islamic Revolutionary Guard Corps (IRGC). Long suspected of building its own bomb, the IRGC has a well-funded, experienced, clandestine procurement network capable of buying and operating centrifuges to enrich uranium as well as building triggering devices. The IRGC already possesses missiles that could deliver a nuke.
Our knowledge of any Iranian nuclear bomb, with only a little exaggeration, is reduced to Google maps, the words of exiles with axes to grind and shady defectors, and studies by think tanks as ill informed as the rest of us.
Not that it's any consolation, but our knowledge about Iran's nukes has always been bad. Since the Shah was in power, the U.S. and Israel put out an estimate every couple of years that Iran was four or five years away from a bomb. But no one ever knew or attempted to explain why Iran ultimately didn't build one mainly because no one was certain as to why.
And then there is the possibility that Iran is playing us in all of this. It wants the world's attention. It wants to be taken seriously. It wants to sit at the table with the G-20. And there's no better way to do this than scaring us with the specter of a nuclear-armed Iran.