American plane (Photo: Michael Reynolds/EPA)

US strikes on three Iranian nuclear sites over the weekend did not destroy key components of the country's nuclear program and likely only delayed it for a few months, CNN reported, citing four unnamed sources familiar with the intelligence reports.

One of them said the previously unreported estimate was prepared by the Pentagon's intelligence unit and is based on a combat damage assessment conducted by U.S. Central Command following the U.S. strikes.

Analysis of damage to facilities and the impact of the strikes on Iran's nuclear ambitions is ongoing and may change as additional intelligence becomes available.

But the preliminary findings contradict repeated statements by US President Donald Trump that the strikes "totally and completely destroyed" Iran's nuclear enrichment facilities.

Two people familiar with the assessment said Iran's enriched uranium stockpile had not been destroyed. One of the people added that the centrifuges were mostly "intact."

"So, the assessment is that the US has delayed it [the nuclear program] for maybe a few months, at most," the person added.

The White House acknowledged the existence of the assessment, but said they disagreed with it.

"The leak of this alleged assessment is a clear attempt to humiliate President Trump and discredit the brave fighter pilots who perfectly executed the mission to destroy Iran's nuclear program," said White House spokeswoman Caroline Leavitt.