The United States and Israel have launched a daylight missile attack on Iran as Donald Trump declared he will 'raze their missile industry to the ground'. 

The US president warned there may be 'US casualties' but said the 'objective is to defend the American people by eliminating the imminent threats from the Iranian regime'.

The first strike, which follows weeks of knife-edge tensions building up between the two countries, happened near the offices of Supreme Leader Ayatollah Ali Khamenei. 

However, officials said the 86-year-old, who has not been seen in public for days, is not in Tehran and has been transferred to a secure location. 

Iran said there would be a 'crushing response' with explosions rocking northern Israel shortly after 8am on Saturday morning. 

The Israeli military said it had identified ballistic missiles launched from Iran towards Israel, with defensive systems operating to 'intercept the threat'.

President Trump announced today the United States had begun 'major combat operations' in Iran with explosions heard in five cities across the country. 

In a video posted to Truth Social, he claimed Iran had continued to expand its nuclear programme and has plans to develop missiles to reach the US. 

The operation in the Middle East has been dubbed 'Epic Fury' by the US Department of Defence, which Trump has renamed the Department of War. 

'We are going to destroy their missiles and raze their missile industry to the ground, it will be totally, again, obliterated,' Trump said in his announcement. 

'We're going to annihilate their navy, we're going to ensure that the region's terrorist proxies can no longer destabilise the region or the world and attack our forces, and no longer use their IEDs or roadside bombs as they are sometimes called, to gravely wound and kill thousands and thousands of people, including many Americans.

'And we will ensure that Iran does not attain a nuclear weapon – a very simple message: They will never have a nuclear weapon.'

A former UK national security adviser said the US and Israeli strikes against Iran were not 'legal in a way that the UK would recognise'.

Lord Peter Ricketts told BBC Radio 4's Today programme: 'None of this, I think, is in any sense legal in a way that the UK would recognise.

'There was really no imminent threat to the US. This is action that they chose to undertake, or were dragged into it by the Israelis.'

In Tehran, witnesses heard the first blast by Mr Khamenei's office on Saturday morning. Iranian state television later reported the explosion, without offering a cause.

There have also been unverified reports of explosions in other locations across Iran including Isfahan, the third biggest city, and Tabriz. 

Israeli Prime Minister Benjamin Netanyahu said the joint attack with the US aimed to 'remove an existential threat posed' by Iran. 

More explosions struck Iran's capital after Israel said it was attacking the country. Authorities have offered no casualty information from the strikes.

Meanwhile, Iran shut down its air space and mobile phone services were cut.

Israel has warned its own citizens to prepare to take cover if the Iranians fight back, with sirens already being heard across Israel.

The country's Defense Force said: 'This is a proactive alert to prepare the public for the possibility of missiles being launched toward the State of Israel.' 

Airspace above Israel was closed to civilian flights following the strike this morning.

The explosions come as tensions are high between Iran and the United States over Tehran's nuclear programme. 

This week Trump made the grave warning that Iran is manufacturing weapons that could soon strike US.

Tehran is 'working on missiles that will soon reach' America, Trump said during his State of the Union address on Tuesday. 

He also vowed to prevent Iran, the 'number one sponsor of terrorism,' from obtaining a nuclear weapon.

Trump has openly flirted with regime change too, telling reporters recently that the ousting of Ayatollah Ali Khamenei 'would be the best thing that could happen.'

But US intelligence reports have not yet concluded that Iran is capable of crafting a weapon capable of reaching the homeland.

The Defense Intelligence Agency (DIA) assessed last year that Iran could need until 2035 to create a 'militarily viable' intercontinental ballistic missile (ICBM) - the kind that travels thousands of miles, including, for a time, through space before the warhead plummets towards its target.

'Iran has space launch vehicles it could use to develop a militarily-viable ICBM by 2035 should Tehran decide to pursue the capability,' the DIA report states.

Two aircraft carrier strike groups - representing around 15,000 soldiers, over a dozen ships, hundreds of planes and likely some submarines - are being used by Trump to get Iran to capitulate to his denuclearization demands.

In addition, many thousands of troops and scores of military assets are on bases throughout the region, though there are some reports of evacuations.

The stalemate has recently shown some signs of traction with Steve Witkoff and Jared Kushner's meeting in Geneva, Switzerland, with chief Iran negotiator Sayyid Badr bin Hamad Al Busaidi, Oman's foreign minister. 

Additional meetings were scheduled for Friday. 

The heated tensions this year come just months after Operation Midnight Hammer - one of the most sophisticated military aviation successes in recent American history.

Last June, Trump's B-2 Stealth Bombers were flown to Iran in a 37-hour secret mission to quell the Middle Eastern country's nuclear capabilities. 

Two dozen Tomahawk land attack cruise missiles hit Iran in the operation.

Their purpose was to neutralize Iranian defense systems protecting nuclear enrichment facilities at Isfahan. When these sites had been destroyed, the B-2 group entered Iranian airspace.

The stealth jet squadron slipped into enemy skies, moving into attack formation at 'high altitude and high speed', with lighter, more mobile F-22 fighter jets sweeping in front of the B-2s to shield them from any surface-to-air or air-to-air fire.

There was none. Not a single shot was fired at any of the aircraft or warships involved in Midnight Hammer from the beginning of the operation to its end.