US B-2 Spirit bombers flew non-stop for about 37 hours from Missouri to strike Iran's three key nuclear sites on Saturday, media reports said.

President Donald Trump on Saturday announced bombing Iran's three nuclear sites and said that with this operation, there would either be peace or more tragedy for Tehran. The sites are Fordow, Natanz, and Esfahan.

The stealth bombers refueled several times mid-air before striking the sites, which Trump described as "spectacular military success."

"Fordow is gone," Trump said, referring to the heavily fortified underground facility long considered Tehran's most secure nuclear site.

He praised the mission as an "amazing success" and warned Iran that they should "make peace immediately or they'll get hit again."

The strikes, carried out with a combination of bunker-buster bombs and Tomahawk missiles, were the most direct US military action against Iran in years.

Trump said six bunker-buster bombs were dropped on Fordow, and around 30 Tomahawk missiles targeted other nuclear installations.

"Tonight, I can report to the world that the strikes were a spectacular military success. Iran's key nuclear enrichment facilities have been completely and totally obliterated. Iran, the bully of the Middle East, must now make peace. If they do not, future attacks will be far greater and a lot easier," he said in an address to the nation.

The Pentagon has confirmed to the media that B-2 bombers were used in the attack, which came after days of rising tensions and a week of escalating hostilities between Israel and Iran.

On Saturday, the US had repositioned B-2 bombers to the Pacific island of Guam.

These aircraft are capable of deploying the GBU-57 Massive Ordnance Penetrator, designed to destroy deeply buried targets like Fordow.

An Iranian official, cited by Tasnim news agency, confirmed damage to part of the Fordow site from "enemy airstrikes."