The new assessment helps create a clearer picture of what the combined Israeli and U.S. strikes on Iran achieved. The bombings deeply damaged Fordo — considered by the Iranians to be their best-protected and most advanced nuclear enrichment site — probably crippling Iran’s ability to make nuclear fuel for years to come.

A new U.S. assessment has found that American strikes in June destroyed only one of three Iranian nuclear sites, NBC News reported on Thursday, citing current and former U.S. officials familiar with the matter.