When the computers that control Iran’s centrifuges were attacked by the Stuxnet worm beginning in 2009, the assault was widely ascribed to intelligence services intent on setting back Iran’s nuclear program. More significant than the damage to Iran, however, has been the damage to Western resolve, as the United States and other countries have become more complacent about the Iranian threat.

Combined with attacks targeting Iranian nuclear scientists and reports of shortages of key materials needed for centrifuges, Stuxnet has given rise to an increasingly accepted narrative that we have more time to contain Iran’s nuclear ambitions than was previously thought.

There’s just one problem with this narrative: It is divorced from reality.

This week the International Atomic Energy Agency (IAEA) Is expected to report new details on Iran’s efforts to design a nuclear device.  This is worrying enough, but the true measure of Iran’s progress toward nuclear weapons capability is the rate at which it is producing enriched uranium. By this measure, Iran is closer than ever to a nuclear weapon and its nuclear enrichment program has not been slowed but, rather, continues to accelerate.

The last IAEA inspection report, issued in September, found almost 6,000 centrifuges spinning at Iran’s enrichment facility at Natanz — more than ever before — and these centrifuges were enriching faster than ever. IAEA data indicate that in the first half of 2011, Iran was able to produce an average of almost 105 kilograms of low-enriched uranium per month. While this monthly rate fell slightly in August, even that was nearly twice Iran’s pre-Stuxnet production rate in 2009 — 56 kilograms per month — and 20 percent higher than its 2010 production rate of 86 kilograms per month. The trend line is clear.

Iran has produced more than 3,000 kilograms of low-enriched uranium and is accumulating more every day. Of course, Tehran would have to enrich this material further to have the highly enriched uranium necessary for a bomb. The fastest route for producing this material will require about 1,850 kilograms of low-enriched uranium to yield the roughly 20 kilograms of uranium enriched to 90 percent that is required for a bomb. Iran’s stockpile of low-enriched uranium is already about 11 / 2 times that amount.

More troubling still has been Iran’s foray into progressively highly levels of uranium enrichment.

Last year Iran began converting uranium it had previously enriched to 3.5 percent to almost 20 percent, ostensibly to fuel a reactor that produces medical isotopes. That reactor annually uses just 7 kilograms of uranium enriched to 20 percent, and IAEA reports indicate that Iran has accumulated almost 50 kilograms of this. In other words, over the past year and a half Iran has produced enough of this material to run its medical reactor for seven years. Nevertheless, Iran declared in June that it intends to triple the rate at which it is producing this material and began transferring this work to a previously secret underground facility at Qom that is carved into the side of a mountain.

In a series of reports, the Bipartisan Policy Center has been tracking the progress of Iran’s nuclear program. We calculate that, if it chooses, Iran could produce enough highly enriched uranium for a nuclear device in just 62 days using its existing stockpiles and current enrichment capability. And international inspectors examine Iranian facilities only about once every two months. This means that Tehran is approaching the ability to produce a bomb’s worth of highly enriched uranium before the international community realizes it has happened.

This timeline will contract substantially if Iran continues on its current course. Because enrichment from 3.5 percent to 20 percent requires about four-fifths of the effort to enrich from 3.5 percent to 90 percent, Tehran’s continued production of uranium enriched to 20 percent will dramatically decrease the time it would need to produce weapons-grade highly enriched uranium. Once Iran acquires more than 150 kilograms of uranium enriched to 20 percent — which could happen by early 2013 if Iran’s announced plans are realized — it would need only 12 days to produce enough fissile material for a bomb.

Now, none of this denies that the Stuxnet worm might have kept Iran’s program from accelerating even more quickly. It appears, for example, that Stuxnet may have caused about 1,000 Iranian centrifuges to fail. According to IAEA data, in May 2009, right before the first known Stuxnet infection, Iran was operating 4,920 centrifuges at Natanz. By January 2010, only 3,772 centrifuges were spinning there. It is also plausible that sanctions have impeded Iran’s ability to purchase materials for new centrifuges.

But these developments are of little comfort if, as IAEA reports demonstrate, Iran’s production of enriched uranium continues to accelerate. Accordingly, there is no basis for concluding that the threat posed by Iran’s program has been diminished. To the contrary, it continues to grow at an alarming rate.

Stephen Rademaker is a principal at the Podesta Group and adviser to the Bipartisan Policy Center. Blaise Misztal is associate director of foreign policy at the Bipartisan Policy Center.