An early assessment of damage to Iran's nuclear sites by an US attack may have only set back that country's nuclear ambitions by a few months, according to an analysis obtained by CNN.

The news agency reported that an initial assessment by the Defense Intelligence Agency suggested that the US strikes on three nuclear facilities in Iran did not destroy the main components of the country's nuclear program, according to unnamed sources.

That finding contrasts with the claims of US president Donald Trump, who said the bunker-buster bombs "completely and totally obliterated" Iran's enrichment facilities.

Two other unnamed sources told CNN that Iran's stockpile of highly enriched uranium survived the attack, and the centrifuges were mostly intact.

"So the assessment is that the US set them back maybe a few months, tops," a source told CNN.

The US launched strikes on three Iranian nuclear facilities on Sunday using numerous B-2 stealth aircraft carrying "bunker-buster" bombs into the airspace of Iran, where they hit nuclear facilities at Fordow, Natanz and Isfahan.

The attack followed days of missile and bomb strikes between Israel and Iran.
On Monday night, Trump announced that the countries were about to begin a ceasefire.