US President Donald Trump said Saturday the US military has carried out a "very successful attack" on three Iranian nuclear sites, including the underground uranium enrichment facility at Fordow.

"We have completed our very successful attack on the three Nuclear sites in Iran, including Fordow, Natanz, and Esfahan," Trump said in a post on his Truth Social platform.

"A full payload of BOMBS was dropped on the primary site, Fordow."

Trump added that "all planes are safely on their way home. Congratulations to our great American Warriors."

Trump's announcement came just two days after he said he would decide "within two weeks" whether to join key ally Israel in attacking Iran.

Earlier on Saturday there were reports that US B-2 bombers -- which carry so-called "bunker buster" bombs -- were headed out of the United States.

Trump did not say what kind of US planes or munitions were involved.

Tehran had threatened reprisals on US forces in the Middle East if Trump attacked but the US president called for "peace."

"There is not another military in the World that could have done this. NOW IS THE TIME FOR PEACE!" he said. (AFP)