A preliminary U.S. intelligence assessment has determined that U.S. strikes over the weekend on Iranian nuclear facilities have set back Tehran's program by only a matter of months, three sources with knowledge of the matter told Reuters.

The initial report was prepared by the Defense Intelligence Agency, the Pentagon's main intelligence arm and one of 18 U.S. intelligence agencies, said two of the sources, who requested anonymity to discuss classified matters.

The assessment found that Iran could restart its nuclear program in a matter of months, according to the three sources, one of whom said it estimated the earliest restart could be in one to two months.

The classified assessment is at odds with the statements of President Donald Trump and high-ranking U.S. officials - including Defense Secretary Pete Hegseth. They have said the weekend strikes, which used a combination of bunker-busting bombs and more conventional weapons, essentially eliminated Iran's nuclear program.

Trump's administration on Tuesday told the U.N Security Council that its weekend strikes had "degraded" Iran's nuclear program, short of Trump's earlier assertion that the facilities had been "obliterated."

Asked for comment, the White House pointed to a statement by spokesperson Karoline Leavitt to CNN, which first reported the assessment, that the "alleged" conclusion was "flat-out wrong."

"Everyone knows what happens when you drop fourteen 30,000 pound bombs perfectly on their targets: total obliteration," she said.

A U.S. official who read the assessment noted that it contained a number of caveats and “ifs” and said a more refined report was expected in the coming days and weeks.

Analysts said that, if the assessment was based on satellite imagery, the extent of damage to the deeply buried Fordow uranium enrichment facility would not necessarily be revealed.

Trump has said the attacks were necessary to prevent Iran from developing a nuclear weapon. Iran denies it is seeking such a weapon and says its nuclear program is for peaceful purposes.

Assessing the damage at the Fordow, Isfahan and Natanz nuclear sites is expected to be a difficult task, and the DIA is not the only agency tasked with the job. One source said the assessment was not universally accepted and had generated significant disagreement.

A U.S. official, speaking on condition of anonymity, said the U.S. did not yet know the true extent of the damage.

Still, the initial assessment indicated the strikes may not have been nearly as successful as the Trump administration has claimed.

A satellite image shows new airstrike craters on an access road to the Fordow Fuel Enrichment Facility, amid the Iran-Israel conflict, near Qom, Iran, June 24, 2025. (Reuters)

HEGSETH REITERATES STANCE

The sources said that the report found that the U.S. attack had caved in facility entrances and destroyed or damaged infrastructure. However, one added, the strike did not collapse underground buildings.

Restarting operations would basically depend on "how long it takes them to dig out and build or repair" power and water supply facilities, said the second source.

The Washington Post, citing a person familiar the report, said some centrifuges for enriching uranium were intact.

The Pentagon disputed the notion that the damage was insignificant, though it did not dispute that the DIA assessment exists.

"Based on everything we have seen — and I've seen it all — our bombing campaign obliterated Iran's ability to create nuclear weapons," Hegseth said in a statement to Reuters.

"Our massive bombs hit exactly the right spot at each target—and worked perfectly. The impact of those bombs is buried under a mountain of rubble in Iran; so anyone who says the bombs were not devastating is just trying to undermine the President and the successful mission."

One source, however, said Iran's enriched uranium stocks had not been eliminated.

David Albright, a former U.N. nuclear inspector, said that based on post-strike commercial satellite imagery, he believed the U.S. attack effectively destroyed Iran's uranium enrichment program for now, but failed to eliminate the longer-term threat.

"Iran retains an ability to break out and produce weapon-grade uranium," said Albright, the head of the Institute for Science and International Security, in a post on X.

He noted that Iran's stock of near-weapons grade highly enriched uranium - enough for about nine warheads - is unaccounted for as are advanced centrifuges for a new enrichment facility that Iran this month told the IAEA it was preparing.

Initial military assessments can change as more information comes to light and it is not uncommon for opinions to vary across different U.S. intelligence agencies.

Democrats have previously said Trump's claims that the weekend strikes eliminated or seriously set back Iran's nuclear program were not yet backed by evidence.

"There's zero evidence that I've seen that the nuclear program was completely and totally obliterated as Donald Trump has claimed," House of Representatives Democratic Leader Hakeem Jeffries said on Monday.

Classified briefings on the matter for members of the House of Representatives and Senate were canceled on Tuesday.

(Reuters)

US strikes may have set back Iran nuclear program only months, sources say