The International Atomic Energy Agency (IAEA) released a report to its Board of Governors this week detailing its findings on Iran’s nuclear program over the last three months. It is clear that the program is steadily progressing. Next week the board will convene in the shadow of the Iranian presidential election to decide how to respond.

In a Q&A, Mark Hibbs explains that Iran’s strategy of negotiating to buy time while continuing unabated with technology development and deployment has been successful. And it means that the case for a limited U.S. or Israeli military intervention to deter Iran from obtaining nuclear weapons loses credibility by the day. 

What does the new IAEA report say about the current state of Iran’s nuclear program?

The most important takeaway is that Iran continues to make steady progress in defiance of sanctions. Meanwhile, Iran’s leaders avoid questions about activities that the IAEA says seem to be related to the development of nuclear explosive devices. IAEA Director General Yukiya Amano said in a television interview on May 21 that Iran needs to “clarify these issues.”

Since the IAEA’s last report in February, Iran has routinely operated its gas centrifuges and increased its stock of uranium hexafluoride (UF6) gas that has been enriched to up to 5 percent uranium 235—typical of the enrichment level needed for power-reactor fuel. Having enriched an additional 689 kilograms during the last three months, Iran now has 6,357 kilograms of this material.

Tehran has also added 44 kilograms to its inventory of 20-percent-enriched uranium (which Iran could quickly enrich further to make nuclear-weapons fuel), increasing that amount to 324 kilograms. It has also continued to convert this UF6 gas centrifuge feedstock into uranium oxide, which is a solid form of uranium that cannot be directly introduced into centrifuges.

According to the report, Iran is still restricting its accumulation of UF6 enriched to 20 percent. By February, Iran had produced 280 kilograms, but it fed all but 167 kilograms into a plant at Esfahan to convert the UF6 to oxide. Of the 44 kilograms added over the last three months, all but 15 kilograms was siphoned off into the conversion process, leaving a total of 182 kilograms UF6.

These numbers mean that Iran has continued producing higher-enriched uranium than that used in most reactors. But it is removing a large share of this material from the enrichment plants producing it and converting the gas output into a solid form that must be converted back to gas in order to be further enriched.

Iran is moving forward on construction of what looks like a plutonium production reactor as well, and it is developing and deploying more powerful centrifuges.

After a decade of uranium fuel production, Iran only has less than half of what it would need to make a single year’s worth of fuel for its Bushehr power reactor. It’s safe to conclude that Iran isn’t enriching uranium to generate electricity for its people.

Politically, Iran’s incremental progress means that sanctions aren’t stopping Iran’s nuclear program.

Why is Iran converting UF6 gas into solid uranium oxide?

No one really knows why Iran is producing this oxide instead of stockpiling most of the 20-percent-enriched uranium it produces in the form of UF6.

Iran says it is converting the gas to solid form to produce fuel for the Tehran Research Reactor (TRR) as well as for four future research reactors. Because of sanctions Iran can no longer import fuel for the TRR. Tehran’s rate of oxide production, however, far outstrips its need for TRR fuel.

On other occasions, Iranians have called the conversion of UF6 to oxide a confidence-building measure to address international concern that Iran is stockpiling 20-percent-enriched gas feedstock that could be quickly enriched further to weapons-grade.

Some officials from Western powers claim instead that Iran is converting the material so as not to provoke military retaliation. While Iran routinely dismisses Israeli threats as bluffing, Western officials assert that Iran is truly worried it will be attacked unless Tehran demonstrates it will to some extent moderate its nuclear advances and not cross certain “redlines” that, if transgressed, might prompt Israeli or U.S. retaliation.

Iran could in principle reconvert all the 20-percent-enriched uranium oxide back into UF6 enrichment feedstock in a matter of a few weeks. Conversion of the gas to oxide in the first place doesn’t rule out using it for the production of nuclear-weapons fuel. It just renders it less convenient.

What is the redline that would provoke military action? Does it impact Iran’s strategy?

The existence of a specific redline has never been publicly confirmed. In 2009, seven years after Iran’s secret construction of an enrichment plant at Natanz was exposed, it was revealed that Tehran was setting up a second clandestine enrichment plant at Fordo. Western states and Israel are worried about that plant for two reasons: it is underground and protected, and it is producing 20-percent-enriched uranium.

After Iran began installing centrifuges at Fordo, Israeli officials urged U.S. counterparts to consider destroying the plant should it begin enriching uranium to 20 percent. In bilateral diplomacy, the United States urged Israel to be patient, but last year media reports asserted that Israel had set a redline at Iran producing enough 20-percent-enriched uranium to make a dash to a bomb by enriching it quickly.

Unconfirmed reports claimed that the redline was 240 kilograms of 20-percent-enriched uranium. In fact, depending on how Iran’s centrifuges are configured, that amount might be about 200 kilograms.

Beginning in the second half of 2012, Iran started to slow its increase in the production of 20-percent-enriched UF6 gas to a trickle. Tehran has kept the total stockpile below the amount that it would likely need to sprint to a bomb.

What does the IAEA report have to say about the likelihood that Iran will try to make a nuclear bomb in a hurry?

Nothing. At the end of the day, what Israel and other states think Iran will do with its growing nuclear assets is based less on Iran’s known capabilities than on Iran’s intentions. We know a lot more about the former than we do about the latter. The answers aren’t found in the fine print of IAEA inventory reports. What matters is how Iran’s track record influences states’ strategic calculations.

Take, for instance, a scenario in which Iran would reconvert its enriched uranium oxide currently under IAEA safeguards into UF6 feedstock, then re-enrich it and make weapons fuel. That is an extreme scenario. And it is not clear that Iran would ever choose to do that. Why, for example, should Iran reconvert its declared uranium oxide back to UF6 if it can keep enriching UF6 with more and more centrifuges, especially if Iran has undeclared UF6 feedstock and undeclared centrifuges?

For nearly all of the parties to the Nuclear Non-Proliferation Treaty (NPT) without nuclear weapons but with complex nuclear-fuel programs like Iran’s, this is a scenario that the IAEA and its member states take into account as theoretically possible but very unlikely. That is because these states by and large have a long track record of cooperation with the IAEA. A few states have on occasion failed to comply with their NPT safeguards obligations. One—Iraq—for a decade tried to make nuclear weapons in secret (and in 1991 in a hurry). And another—North Korea—quit the NPT and then made nuclear explosives.

Unlikely reconversion scenarios cannot be dismissed lightly for Iran because the record of Iran’s relationship with the IAEA does not inspire confidence. For nearly twenty years, Iran systematically deceived the IAEA about the extent of its nuclear activities. To this day Iran has failed to fully cooperate—as the new report explains—with regard to unanswered questions about allegations of weapons-related work and in not making timely declarations. There’s also the possibility that diplomatic efforts with Iran will fail and that Iran, in response to sanctions and/or military aggression, might leave the NPT.

What does the report say about the approach taken by the international community?

The bottom line is that while there is a rationale for the sanctions that have been imposed over the years, they haven’t succeeded in halting Iran’s nuclear program.

And continued progress means that Iran is piling up nuclear assets that are essentially bargaining chips in its negotiations with the P5+1 (China, France, Russia, the United Kingdom, and the United States plus Germany). The more centrifuges, reactors, enriched uranium, and other nuclear goods Iran has, the greater Iran’s leverage vis-à-vis adversaries that launched a diplomatic effort back in 2003 to curtail Tehran’s nuclear activities.

Western states, beginning in 2003, sought “zero enrichment” by Iran. From the outset, every additional centrifuge Iran has deployed and each additional kilogram of enriched uranium Iran has stockpiled has made this outcome ever more unlikely. Continued Iranian progress will further erode the powers’ bargaining strength.

How will the IAEA’s Board of Governors and the powers negotiating with Iran respond to the report?

Last September the board passed a resolution that backed efforts in Western states to impose new sanctions on Iran. Tehran continues to balk—demanding this month that the IAEA close its investigation in return for more cooperation from Tehran. But with Iran’s presidential election scheduled for June, the powers may avoid pressing for a further resolution that might prompt confrontation at the IAEA board meeting next week.

Diplomacy has not shown significant progress in part because Tehran and Washington have been guided by deep mutual suspicion but also fear of domestic political opposition. U.S. President Obama and his advisers have not been willing to take any significant political risk on Iran. Ayatollah Khamenei’s backing of hardline presidential candidates likewise suggests he sees engagement with the West as potentially politically fatal.

Western powers are also reluctant because over the last ten years, Iran has effectively used quarterly IAEA board meetings as an opportunity to buy precious time for its nuclear program by dangling carrots and then pulling back. The IAEA report underscores that this tactic has paid off but also that the diplomatic status quo is not a solution because Iran is piling up bargaining chips.

This implies that with every passing day, the case for a military attack to “take out” Iran’s nuclear capability is less credible. The only way out may be a far more ambitious offer from the powers to Tehran that addresses Iran’s quest for status and security. But no one knows whether the supreme leader and his entourage would be prepared to make a deal.