President Donald Trump says the US has carried out a “successful” bombing attack on three nuclear sites in Iran and that they have been “obliterated”.

Israel says they were in “full co-ordination” with the US in planning the strikes. Iranian officials have confirmed the facilities were struck but denied it had suffered a major blow.

The strikes mark a significant escalation in the ongoing war between Iran and Israel.

Here’s what we know.

One of the targets was Fordo, a uranium enrichment plant hidden in a remote mountainside that is vital to Iran’s nuclear ambitions. We do not yet know the full scale of the damage at the facility.

The US says it also hit two other nuclear sites – at Natanz and Isfahan.

Hidden away in a mountainside south of Tehran, Fordo is believed to be deeper underground than the Channel Tunnel connecting the UK and France.

Due to Fordo’s depth below ground only the US has the kind of “bunker buster” bomb big enough to destroy the site. That US bomb is called the GBU-57 Massive Ordnance Penetrator (MOP).

It weighs 13,000kg (30,000lb) and is able to penetrate about 18m (60ft) of concrete or 61m (200ft) of earth before exploding, according to experts.

Due to the depths of Fordo’s tunnels, the MOP is not guaranteed to be successful, but it is the only bomb that could come close.

US media reports say MOPs were used in the strikes.

It is unclear yet what damage the US attack has had on the nuclear facilities, or whether there are any injuries or casualties.

The Iranian Atomic Energy Organization said the bombing of the three nuclear sites was a “barbaric violation” of international law.

Both Saudi Arabia and the United Nations’ nuclear watchdog say there have been no increase in radiation levels after the attack.

The deputy political director of Iran’s state broadcaster, Hassan Abedini, said Iran had evacuated these three nuclear sites a “while ago”.

Appearing on state-run TV, he said Iran “didn’t suffer a major blow because the materials had already been taken out”.

In his televised address, Trump said the “nuclear enrichment facilities have been completely and totally obliterated”.

But speaking on the BBC News Channel, former US assistant secretary of state for political-military affairs Mark Kimmitt was more circumspect.

“There’s no way to suggest that it has been destroyed for all time,” he said.

Iran’s foreign minister has warned the US that its attack on Fordo, Isfahan and Natanz will have “everlasting consequences.”

Abbas Araghchi said Iran was reserving “all options” to defend its sovereignty.

Since Israel launched a surprise attack on dozens of Iranian nuclear and military targets on 13 June, Iran has been weakened significantly, experts say.

Iran is still capable of doing a considerable amount of damage.

Previously, Iranian officials warned the US against getting involved, saying it would suffer “irreparable damage” and that it risked an “all-out war” in the region.

BBC security correspondent Frank Gardner says Iran must now choose between three strategic courses of action in response to the US attack overnight:

• Do nothing. This could spare it from further US attacks. It could even choose the diplomatic route and re-join negotiations with the US. But doing nothing makes the Iranian regime look weak, especially after all its warnings of dire repercussions if the US did attack. It may decide the risk of weakening its grip on its population outweighs the cost of further US attacks
• Retaliate hard and fast. Iran still has a substantial arsenal of ballistic missiles after manufacturing and hiding these away for years. It has a target list of around 20 US bases to choose from in the broader Middle East. It could also launch “swarm attacks” on US Navy warships using drones and fast torpedo boats
• Retaliate later at a time of its own choosing. This would mean waiting until the current tension has subsided and launching a surprise attack when US bases were no longer on maximum alert

The US operates military sites across at least 19 countries in the Middle East, including Bahrain, Egypt, Iraq, Jordan, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates.

Among the most obvious targets for Iran is the US Navy’s 5th Fleet HQ at Mina Salman in Bahrain.

It could also target shipping lanes in the Strait of Hormuz, which links the Persian Gulf to the Indian Ocean and through which 30% of the world’s oil supply is transported. It could also attack other sea routes that risk destabilising global markets.

Iran could also target the assets of nearby countries it perceives to be aiding the US, which risks the war spilling over to the entire region.

In the hours after the US bombing, Iran launched a fresh wave of missiles towards Israel. Explosions were heard over Haifa, Tel Aviv and Jerusalem.

Flanked by Vice President JD Vance, Defence Secretary Pete Hegseth and Secretary of State Marco Rubio, Trump said in his address that future attacks would be “far greater” unless Iran reached a diplomatic solution.

“Remember, there are many targets left,” he said.

Several members of Trump’s Republican Party have posted statements in support of the move. Texas Senator Ted Cruz “commended” the president, his administration and the US military involved in the strikes.

However, leading US Democrat Hakeem Jeffries said Trump risked US “entanglement in a potentially disastrous war in the Middle East”, while others have accused him of bypassing Congress to launch a new war.

Independent Senator Bernie Sanders described the US strikes as “grossly unconstitutional” as the president does not have the sole power to formally declare war on another country. Only Congress – lawmakers elected in the House of Representatives and the Senate – can.

But the law also states that the president is the commander in chief of the armed forces. That means he can deploy US troops and conduct military operations without a formal declaration of war.

Israel launched a surprise attack on dozens of Iranian nuclear and military targets on 13 June. It said its ambition was to dismantle its nuclear programme, which Prime Minister Benjamin Netanyahu said would soon be able to produce a nuclear bomb.

Iran insists its nuclear ambitions are peaceful. In retaliation, Tehran launched hundreds of rockets and drones at Israel. The two countries have continued exchanging strikes since, in an air war which has now lasted more than a week.

Trump has long said that he is opposed to Iran possessing a nuclear weapon. Israel is widely believed to have them, although it neither confirms nor denies this.

In March, US national intelligence director Tulsi Gabbard said that while Iran had increased its uranium stockpile to unprecedented levels, it was not building a nuclear weapon – an assessment that Trump recently said was “wrong”.

On the campaign trail, Trump had criticised past US administrations for engaging in “stupid endless wars” in the Middle East, and he vowed to keep America out of foreign conflicts.

The US and Iran were in nuclear talks at the time of Israel’s surprise attack. Only two days ago, Trump said he would give Iran two weeks to enter into substantial negotiations before striking – but that timeline turned out to be much shorter.