A new U.N. report asserting that Tehran has enriched uranium particles to 83.7 percent purity has thrust the Biden administration into tough choices

By Karen DeYoung and  Joby Warrick 

The discovery in Iran of a small quantity of uranium enriched to near bombmaking level has increased U.S.-Iranian tensions already stretched tight by moribund nuclear talks and Tehran’s aid to Moscow’s war effort in Ukraine.

The nuclear alarm also comes as the Biden administration — walking a diplomatic tightrope as it criticizes domestic policies of Israel’s new ultra-rightwing government while maintaining strong security cooperation — appears to have softened its public resistance to potential Israeli military action against Iran.

Uranium “particles” enriched to nearly 84 percent purity were detected during a routine sampling by inspectors from the International Atomic Energy Agency at Iran’s Fordow nuclear site last month, the agency said in a restricted report circulated among IAEA member states on Wednesday. The particles are only slightly below the 90 percent enrichment level regarded as weapons-grade, or suitable for use in nuclear weapons.

Until the Trump administration’s unilateral withdrawal from the Iran nuclear deal in 2018, Iran was known to produce only low-enriched uranium to fuel of the kind used in nuclear power plants or for medical purposes. In recent years, however, Tehran has blown past many of the accord’s restrictions, stockpiling uranium enriched to up to 60 percent.

The new report “places Iran on the cusp of weapons-grade fissile material,” said Robert Litwak, a nonproliferation expert and director of international security studies at the Woodrow Wilson International Center for Scholars.

Iran has long denied seeking nuclear weapons, but many experts believe the regime wants to assemble the key ingredients for a nuclear bomb so it can build one quickly in the future if it decides to do so, a window known as “breakout time. ”

“Iran’s strategic sweet spot is a hedge — maintaining the option for a weapon without crossing the overt line of weaponization,” Litwak said.

The discovery of the particles, while previously reported in recent days, was confirmed in the 18-page IAEA report documenting Iran’s continuing defiance of the original 2015 nuclear agreement signed with world powers, including the United States.

The deal limited stockpiling to about 660 pounds of uranium enriched to no more than 3.57 percent and mandated strict IAEA monitoring in exchange for the lifting of harsh U.S. and international sanctions. Trump reimposed those sanctions — and levied additional economic punishments — following his administration’s withdrawal from the agreement.

The bulk of the current stockpile was enriched to less than 5 percent, although Iran has acknowledged enrichment of up to 60 percent, according to the report. When the aberrant samples, enriched to 83.7 percent, were found at the Fordow facility, about 20 miles northeast of the city of Qom, the IAEA promptly notified Tehran and asked for an explanation.

“Discussions between the Agency and Iran to clarify the matter are ongoing,” the report said.

Iran said last week that the high number reflected only “unintended fluctuations” during the upgrading of enrichment centrifuges. On Wednesday, the head of Iran’s Atomic Energy Organization, Mohammad Eslami, said without further detail that the matter had been “resolved,” and that there has been “no deviation” in Iran’s commitment to only peaceful nuclear activities, Iranian media reported.

But Iran’s explanation drew immediate skepticism. “Not very plausible without a lot more evidence from the other side,” said David Albright, president of the Institute for Science and International Security, a Washington nonprofit that researches nuclear weapons programs.

Albright said the report’s revelations about the size of Iran’s stockpile shows that it is nearing the point where it could develop a nuclear weapon quickly. Using the nearly 200 pounds of 60 percent enriched uranium reportedly now on hand, Iran could further process the fuel into a bomb’s worth of weapons-grade uranium in as little as 12 days, he said.

Pentagon policy chief Colin Kahl offered that breakout time in House testimony Tuesday. Asked by Republican lawmakers why the Biden administration had attempted to revive the 2015 agreement, Kahl said, “because Iran’s nuclear progress … has been remarkable” since the U.S. withdrawal from the deal.

Before, “it would have taken Iran about 12 months to produce one bomb’s worth of fissile material. Now it would take about 12 days,” he said, shortening the “few weeks” assessment used by the administration over the past year.

The ominous nuclear report comes as the Biden administration has charged Iran with forming an ever-closer military relationship with Russia, which is “moving at a pretty fast clip in a very dangerous direction right now,” CIA Director William J. Burns said Sunday on CBS’s Face the Nation.

“We know that the Iranians have already provided hundreds of armed drones to the Russians which they’re using to inflict pain on Ukrainian civilians and Ukrainian civilian infrastructure,” as well as providing artillery and tank ammunition, Burns said. “And what we also see are signs that, you know, Russia is proposing to help the Iranians on their missile program and at least considering the possibility of providing fighter aircraft to Iran as well.”

Repeating previous intelligence assessments, Burns said that despite the rapid escalation in Iran’s nuclear enrichment program, “we don’t see evidence that they made a decision” to resume what U.S. intelligence has said was a weaponization program Tehran shut down in 2003.

Burns also voiced concern about Iran’s ballistic missile program, noting that “their ability to deliver a nuclear weapon, once they developed it, has also been advancing as well.”

President Biden has said repeatedly that he will not allow Iran to obtain a nuclear weapon, and that “all options” remain on the table to prevent it. Talks his administration began on reviving the nuclear deal are currently off the table as both sides held to hard lines. But the administration still maintains that the best way to resolve the conflict with Iran is through diplomacy.

Israel, which opposed the original nuclear deal and objects to its revival, has maintained the right to take whatever military action it deems necessary against a regime in Tehran that has at least rhetorically called for wiping Israel off the face of the earth. Israel’s intelligence and military are suspected of multiple attacks on Iran, including unsolved assassinations of key Iranian nuclear scientists and cyberattacks. The U.S. position has long been to deny pre-knowledge or tacit approval of such action.

But a comment last week by U.S. ambassador to Israel Thomas Nides seemed to shift the balance. “Israel can and should do whatever they need to deal with [Iran] and we’ve got their back,” he said.

Asked whether Nides’s remarks now constituted a “green light,” Secretary of State Antony Blinken told reporters that the administration still believes in a diplomatic solution to its problems with Iran.

But “in the meantime, of course, we’ve seen the provision by Iran of drones to Russia to enable its aggression in Ukraine,” Blinken said. “We’ve seen the renewed repression throughout the streets of Iran against its own citizens simply for trying to speak their minds. And we see Iran also engaging, for example, in plots to assassinate those who oppose the regime in third countries, including in the United States.”

At the same time, however, the Biden administration has sharply increased its criticism of the government of reelected Prime Minister Benjamin Netanyahu’s right-wing coalition, which includes several extremist parties.

On Wednesday, State Department spokesman Ned Price described remarks by Finance Minister Bezalel Smotrich, who heads the far right Religious Zionism party, as “repugnant,” “disgusting” and an “incitement to violence,” and called for “senior Israeli officials to publicly and clearly reject and disavow” them.

Smotrich had said that the Palestinian town of Huwara “needs to be erased” after the shooting deaths of two Israeli brothers was followed by a revenge rampage by Israeli settlers resulting in at least one Palestinian death, hundreds of others wounded, and dozens of homes burned.

In a Wednesday evening interview on CNN, Israeli Ambassador to the United States Michael Herzog said that “notwithstanding” a recent wave of Palestinian attacks, “it is absolutely not Israeli policy and it’s against our values to respond by wiping out civilian villages.”

John Hudson contributed to this report.