The United Nations’ top nuclear watchdog told CBS News that Iran could revive parts of its nuclear program, though U.S. military strikes have dented it — and said any mission to recover Iran’s stockpiles of enriched uranium would be extremely difficult.
Rafael Grossi, director-general of the International Atomic Energy Agency, spoke with “Face the Nation” moderator Margaret Brennan on Thursday, as the U.S. and Israel’s war with Iran nears the three-week mark. President Trump has pointed to Iran’s nuclear program as one catalyst for the war, accusing Iran of harboring ambitions to build nuclear weapons, which Iran denies.
Grossi spoke about the likely state of Iran’s nuclear program, the prospect of restarting it and whether a deal to curb the program was possible before the war.
Here are the biggest takeaways:
After war ends, “we will still inherit a number of major issues”
Grossi said U.S. military action has degraded Iran’s nuclear program — but parts of the program have survived, and Iran still has the technical know-how to enrich uranium.
Last June’s U.S. bombing campaign against three Iranian nuclear facilities — the Fordo and Natanz enrichment sites and the Isfahan research site — was “quite effective,” Grossi said. Some strikes have also been reported on nuclear facilities in the current military operation, though Grossi said they have been “relatively marginal” considering the war’s broader scope.
“One cannot deny that this has really rolled back the program considerably,” he said. “But my impression is that once the military effort comes to an end, we will still inherit a number of major issues that have been at the center of all of this.”
Those lingering issues include Iran’s stockpile of 60%-enriched uranium, which is a short step away from weapons-grade material, and some facilities that have likely survived the U.S. bombing campaign, according to Grossi.
Director of National Intelligence Tulsi Gabbard testified to lawmakers this week that Iran did not attempt to rebuild its uranium enrichment capabilities following the June strikes. Grossi said the IAEA also has not “seen activity” suggesting a rebuilding effort.
But “a lot still has survived,” Grossi added. “They have the capabilities, they have the knowledge, they have the industrial ability to do that.”
Military operation to remove highly enriched uranium would be “very challenging”
Before last June’s airstrikes, the IAEA assessed that Iran had enriched some 972 pounds of uranium to 60% purity. According to the IAEA’s metrics, about 92.5 pounds is theoretically enough to build a single nuclear weapon if enriched to 90%.
Much of that material is likely still buried underneath the rubble, Grossi noted.
Mr. Trump has not made up his mind on whether to send U.S. forces into Iran to seize that material in what would be a dangerous operation, CBS News reported earlier this week. White House press secretary Karoline Leavitt did not rule out the idea, telling reporters a ground operation is “an option on the table for him.”
Grossi said recovering that material would be tough.
“We’re talking about cylinders containing gas of highly contaminated uranium hexafluoride at 60%, so it’s very difficult to handle,” he said. “I’m not saying it’s impossible. I know that here there are incredible military capacities to do that, but it would be [a] very challenging operation for sure.”
Grossi noted that when the U.S. and Iran held indirect peace talks prior to the war, negotiators discussed “downblending” Iran’s highly enriched uranium to make it easier to handle.
Iran can rebuild centrifuges: “You cannot unlearn what you’ve learned”
Grossi said he believes it would be “very possible to reconstruct” Iran’s enrichment program.
Even if airstrikes have destroyed many of Iran’s centrifuges, the knowledge required to build them cannot be bombed away, Grossi noted.
“You cannot unlearn what you’ve learned,” he said.
Grossi described a centrifuge — which enriches uranium by spinning at high speeds to separate out a fissile isotope of uranium called U-235 — as a “sophisticated washing machine.”
He added that the 2015 nuclear deal between the U.S. and Iran was predicated on Iran having “very primitive” centrifuges, but since then, Iran has developed “the most sophisticated, fast and efficient machine that exists, and they know how to make them.”
Was a nuclear deal to avert war with Iran possible?
In the weeks leading up to the current war, negotiators from the U.S. and Iran held several rounds of indirect talks over Iran’s nuclear program. Hours before the U.S. and Israel’s bombing campaign began in late February, Omani Foreign Minister Badr Albusaidi, who mediated the negotiations, told CBS News that a “peace deal is within our reach.”
Albusaidi described the broad contours of a potential U.S.-Iran deal, including an Iranian agreement to “never, ever have … nuclear material that will create a bomb,” and a plan to blend down Iran’s existing stockpiles of highly enriched uranium.
Grossi said a deal with Iran had not yet been reached, but “while there’s a negotiation, there’s always a possibility of an agreement.” Prior to the start of hostilities, negotiators were set to hold technical talks in Vienna, home to the IAEA’s headquarters, he pointed out.
“We were having very frank and very deep discussions. So one cannot deny the nobility of the effort of someone who’s trying to prevent a war, and I applaud that as a diplomat and as a citizen,” he said. “But there was no agreement at that point.”
Was the Tehran Research Reactor a problem?
One apparent stumbling block in the U.S.-Iran negotiations was the Tehran Research Reactor, a 1960s-era nuclear reactor that the U.S. supplied to Iran before the country’s current regime rose to power during the Islamic Revolution. The reactor — which can produce nuclear material for medical purposes — is powered by 20%-enriched uranium, which is a significant step toward the 90%-enriched material used in weapons.
But Mr. Trump had pushed for Iran to end all uranium enrichment, preventing it from making fuel for the research reactor. A 2015 nuclear deal between Iran, the U.S. and several other major powers — which Mr. Trump withdrew from during his first term — only allowed Iran to enrich uranium to 3.67%, though it said Iran can buy fuel for the Tehran facility from abroad if needed.
After the war started, a senior Trump administration official alleged to reporters that Iran was actually stockpiling uranium at the research reactor, calling claims that it was needed for medical purposes a “false pretense.” The official said U.S. negotiators made that discovery with the help of the IAEA, which revealed that Iran had stored more fuel at the facility than necessary.
Asked about those allegations, Grossi said his role is to provide technical expertise, not to weigh in on whether Iran was honest or dishonest. But he said that “20% is a lot of enrichment.”
Grossi noted that “we were in the middle of a negotiation which was proceeding from the assumption that there wouldn’t be any enrichment,” or “something very, very limited.”
“So … when you talk about 20%, you are exceeding that amount. Forget about if there was [a] stockpile or not,” said Grossi.
The “new stuff” the IAEA saw in Iran
The U.S. intelligence community assessed last spring that Iran was not actively building a nuclear weapon, and a prior weaponization program was suspended in 2003. But in recent years, Iran has enriched uranium to 60%, near the level required to build a bomb. (Iran has long denied any interest in building a nuclear weapon and says its program is peaceful.)
Grossi told CBS News that “we haven’t seen a systematic program” like the alleged nuclear weapons development program that existed prior to 2003.
“But there were many, many concerning things, many unanswered questions,” said Grossi.
He said that after he became the IAEA’s director-general in 2019, a year and a half after Mr. Trump withdrew from the Obama-era nuclear deal, “we started seeing new stuff. We started seeing and getting new elements that gave rise to concerns, and we were talking about them with Iran.”
He said those concerns included the discovery of uranium particles in places that Iran had not formally declared as nuclear sites, which Grossi described publicly in a 2024 statement.
Last year, the IAEA formally declared that it “is not able to verify that there has been no diversion of nuclear material … to nuclear weapons or other nuclear explosive devices.”
