The US struck a facility in the mountain ridge in Isfahan, where a stockpile of enriched uranium and facilities related to the nuclear program were likely held, a source familiar with the details of the US operation told The Jerusalem Post.
Sources added that the Natanz nuclear site has been destroyed, while the Fordow and Isfahan sites suffered "major damage", but it is unknown yet how much.
Earlier on Sunday, satellite imagery from Iran’s Fordow nuclear facility showed the possible bomb entry points and possible subsidence of the site following the US overnight strikes on Iranian nuclear facilities.
US President Donald Trump said that Iran's three main nuclear enrichment facilities, namely Fordow, Natanz, and Isfahan, have been "completely and totally obliterated" in an address from the White House Saturday night.
"Our objective was the destruction of Iran's nuclear enrichment capacity and a stop to the nuclear threat posed by the world's number one state sponsor of terror," he said, adding that the strikes were a "spectacular military success."
"We have completed our very successful attack on the three Nuclear sites in Iran, including Fordow, Natanz, and Esfahan. Congratulations to our great American Warriors. There is not another military in the World that could have done this," Trump added.
Prior to the US attack, estimates were that a strike on Fordow, following Israel having already mostly destroyed Natanz and Isfahan, would push off the nuclear program by a minimum of six months, with many coming in at two years, and some thinking the delay of the Islamic Republic's nuclear threat could even be longer.
Israeli and US intelligence estimates to The Jerusalem Post had been that only the US's 30,000-pound (MOAB) bomb, specifically its Massive Ordnance Penetrator (MOP) variant, could completely destroy Fordow.
Was Fordow destroyed during the US strike?
This estimate was given due to the fact that Fordow is located under a mountain, and that Israeli attacks would only damage or cause cave-ins to delay the use of the nuclear site for a shorter period of time.
Initial estimates are that Fordow is not only partially damaged or caved in, but destroyed.
Some Israeli officials told the Post they believe Fordow was destroyed, while others said caution should be the rule until confirmation is given.
Yonah Jeremy Bob contributed to this report.