The US has bombed three of Iran’s nuclear facilities, Donald Trump has announced, in an assault that threatens to bring the two countries to war. 

The US president authorised the bombings of the underground Fordow plant, one of the country’s key nuclear sites, and two other facilities in the early hours of Sunday morning, calling it a “successful attack”.

“We have completed our very successful attack on the three nuclear sites in Iran, including Fordow, Natanz, and [Isfahan],” Mr Trump said on Truth Social.

“All planes are now outside of Iran air space. A full payload of bombs was dropped on the primary site, Fordow. All planes are safely on their way home. Congratulations to our great American Warriors. 

“There is not another military in the World that could have done this. NOW IS THE TIME FOR PEACE! Thank you for your attention to this matter.”

In what is the most consequential decision of Mr Trump’s presidency so far, the assault signals a significant escalation in the conflict with Tehran.

Pressure had been mounting on the US to intervene in the escalating conflict in support of Israel, and to force Iran’s leaders to end its nuclear programme.

Amid the prodding of Israeli officials and many Republican lawmakers, Mr Trump had approved plans for a US strike on Iran earlier this week but had not yet given a final order.

On Saturday, the green light was given to strike the Fordow plant, Iran’s most heavily fortified and primary nuclear facility.

It came after officials revealed earlier that day that B-2 stealth warplanes and refuelling tankers had left their Missouri base for the Pacific base of Guam.

The plant, 20 miles from the central city of Qom, is considered so naturally protected that there is just one weapon in the world able to blow it up.

The US’s 30,000lb GBU-57F/B Massive Ordnance Penetrator bomb, or “Mop”, can penetrate around 60 metres underground before exploding.

Officials fear weapons-grade uranium and hazardous raw materials were being manufactured at the site, and experts had warned a strike could have severe effects.

B-2 stealth bombers armed with six of the bunker-busting bombs were used in the strike, Fox News reported. The White House and Pentagon did not immediately elaborate on the operation.

The weapon is thought to be able to penetrate through 61 metres of concrete and is considered the only weapon able to directly threaten the site itself. 

It can only be dropped by a B-2 stealth bomber, which can carry two at a time. 

The bomb is designed to penetrate and detonate at the maximum possible depth to neutralise interred threats such as bunkers.