For nearly five years, the world has watched Iran pursue a uranium-enrichment program aimed at making fuel for nuclear power plants--or for nuclear weapons. The Iranian program is based on cascades of gas centrifuges, groups of large, spinning tubes that process, or enrich, uranium. One year ago this week, Iran announced, to widespread concern, that it had enriched uranium to a level suitable for use in power plants, a task it accomplished using a cascade of 164 centrifuges. Despite strong warnings, Iran has continued to defy international demands that it stop. So, when Iranian President Mahmoud Ahmadinejad claimed earlier this week that Iran now had an "industrial" enrichment capability--based on a newly installed group of 3,000 centrifuges--it seemed reasonable to react in two ways simultaneously. On the one hand, with alarm: Iran appears to be much closer to a nuclear weapons capability than most had previously suspected. On the other hand, by seizing an opportunity: By announcing its progress so boldly, Tehran has offered the United States and its allies a chance to spotlight the Iranian threat and rally the world to oppose it.

But Iran's claim merits neither response. Its progress is actually much less than meets the eye. It has developed nothing remotely resembling an industrial capacity to enrich uranium, nor is there any evidence that it has made surprising new strides toward a nuclear weapon. And taking the Iranian claims at face value would be worse than error; it would be a strategic miscalculation that could help entrench the Iranian nuclear program and make it even more difficult to oppose.

According to the "Iran Dossier" prepared by the International Institute for Strategic Studies, 3,000 first-generation Iranian centrifuges operating perfectly for approximately one year could produce enough fissile material to fuel one nuclear bomb. That makes the Iranian announcement sound pretty scary. But it's far from clear that Iran can come anywhere close to perfection in operating its machines. David Albright recently estimated, based on data published by the International Atomic Energy Agency (IAEA), that the centrifuges in Iran's 164-machine cascade were operating roughly 20 percent of the time. If the new 3,000-centerfuge plant functions at that level, it would take five years for it to produce enough material for a bomb. There is, of course, an outside chance that Iran has made immense technical leaps in recent years; but we shouldn't let worst-case fears that lack hard evidence dominate our policymaking.

Moreover, as Jeffrey Lewis has noted, Iran has so far used less than one ton of uranium hexafluoride, the form of uranium used in a centrifuge plant. That number has special significance. Iran bought what experts call "hex" from China back in 1991--one ton's worth, enough for the work Tehran has completed so far. But Iran's homemade hex is thought to be of poor quality: If the Iranians fed it into their centrifuges, the machines could break down. So, if Iran has used only Chinese uranium to date, even its shaky performance so far may overstate its capabilities, since, according to my calculations, it would need at least seven tons to make a bomb. It's possible Tehran has acquired more high-quality hex elsewhere, but IAEA investigations suggest that this is unlikely.

Nor would the Iranian facility be industrial scale even if it were functioning perfectly. Common sense demands that an industrial-scale enrichment plant be able to support a nuclear industry. A simple estimate, though, shows that the new facility would take roughly ten years to produce the fuel needed to operate Iran's single nuclear power plant for one year. If the Iranian facility is industrial scale, then my kitchen is a bakery.

These word games matter. By announcing an industrial capability, the hardline Iranian president has drawn a new line--any attempts to scale down the Iranian program, coming either from the international community or from his more pragmatic and moderate domestic opponents, can now be labeled as efforts to strip Iran of its industrial strength. Such rhetoric may resonate within Iran, where most citizens see the nuclear program as economic in nature, as well as with other developing nations. Ahmadinejad has also now claimed credit for what is seen in Iran as a major scientific advance, further strengthening him domestically. But, rather than take his p.r. stunt at face value, we should challenge it--not least because doing so will undermine whatever strength the hardliners have gained.

It's true that trusting the Iranian claims could, in theory, help build international opposition to Tehran: Since industrial-scale enrichment requires far more centrifuges than enrichment for weapons does, this should be particularly terrifying. But people around the world won't be doing the math. And believing Ahmadinejad's "industrial" appellation lets him paint a benign, civil image of his efforts. We shouldn't let that happen.

None of this means we should underestimate the threat posed by Iran. But a solution will require a mix of carrots and sticks that can compel Tehran to surrender its program--or, more likely, empower those elements of Tehran's leadership more inclined to compromise with the West. Exaggerating Iran's danger doesn't particularly help us--we're already quite wary enough--but it does strengthen those who can do us the most harm.

By Michael Levi