A critical juncturepublished at 13:06 British Summer Time 18 June

13:06 BST 18 June

Frank Gardner
Security correspondent

This conflict has now reached a critical juncture. What Donald Trump decides to do or not to do could shape what happens next in the Middle East.

Today’s televised broadcast from Iran’s Supreme Leader, Ayatollah Ali Khamenei, has dispelled any misguided hopes that the Islamic Republic was about to sue for peace.

On the contrary, the ageing Ayatollah has thrown down his own gauntlet to Trump, threatening dire retaliation if America joins in Israel’s attacks.

Iran may have been severely weakened, not just by the last few days’ sustained Israeli air strikes but by the loss or dismantling of its regional proxies in Lebanon, Syria and Gaza.

But it can still do a lot of damage. Top of its target list if the US attacks Iran will be the numerous US bases spread up and down the Gulf. The US Navy’s 5th Fleet HQ at Mina Salman in Bahrain is an obvious target but so too are America’s bases in Iraq and Kuwait.

But it doesn’t end there. The September 2019 massed drone attack on Saudi Arabia’s petrochemical industry was a salutary lesson in just how vulnerable the Gulf’s economic assets are to Iranian missiles and drones.

If the Iranian regime felt its very survival was in danger, or if it decided its Gulf Arab neighbours were complicit in attacking it then it could well be tempted to lash out at desalination plants, oil export terminals or even mine the strategic Strait of Hormuz, choking off nearly 30% of the world’s oil supplies.

Ghoncheh Habibiazad
BBC Persian

Image source, EPA

Iran state TV just showed the televised message of Iranian Supreme Leader Ali Khamenei in full.

He says that “the Americans, and those familiar with the politics of this region, know that the US involvement in this matter will be entirely to its detriment and it will suffer a blow.”

“A blow that will be far more damaging than any harm that may come to Iran.

Khamenei also calls Donald Trump’s demand for Iran to surrender “irrational”, saying, “threats do not have an impact on the thoughts or behaviour of the Iranian nation”.

Latest satellite imagery shows damage to Iranian missile base and airportpublished at 12:44 British Summer Time 18 June

12:44 BST 18 June

By Joshua Cheetham

The BBC along with other international media cannot report from inside Iran, so satellite imagery is a key tool for us to see and verify what is happening in the country as Israel’s attacks continue.

The latest pictures have come to us from the specialist satellite imaging firm Maxar. They appear to show extensive damage to Tabriz missile base with at least nine buildings and two tunnel entrances destroyed. Several others are heavily damaged.

Maxar’s imaging has also captured potential evidence of strikes against Mashhad airport, about 750km (470 miles) east of Tehran. We can see a large aircraft has been destroyed, with only the tail left intact.

Another image shows what Maxar describe as Shahed drones stored on trailers and fighter aircraft at Dezful air force base in western Iran.

We’ve shared these images with experts to get a better understanding of what’s been targeted, and what impact this will have on Iran’s military capability.

Trump's Iran dilemma exposes split among Republicanspublished at 12:23 British Summer Time 18 June

12:23 BST 18 June

Bernd Debusmann Jr & Max Matza
BBC News

Image source, Reuters

The dilemma of whether the US should join Israel in attacking Iran, or stay out of the offensive altogether, has exposed divisions among US President Donald Trump's supporters.

The Republican president reportedly is considering helping target the Islamic Republic's nuclear facilities, following a meeting with his national security advisers in the White House Situation Room on Tuesday.

Several proponents of Trump's "America First" doctrine have pointed out that he vowed to keep the US out of "forever wars" such as those that led to the deaths of thousands of US troops in Afghanistan and Iraq.

Other warhawks in the party are egging on Trump to target Iran.

South Carolina Senator Lindsey Graham said it was in the national security interests of the US to prevent Iran from obtaining a nuclear bomb. Tehran maintains its nuclear programme is for peaceful, civilian purposes such as energy.

• Read the full analysis on the divide between Republicans over the war in Iran

Image source, Reuters

As Iran's Ayatollah Ali Khamenei responds to Israel's strike in an address via state broadcasters, let's take a look back at news from yesterday that Washington is considering supporting Israel's offensive.

Trump is reportedly "considering" joining Israel's strikes against Iranian nuclear sites, the BBC's US partner CBS news reported.

One potential target could be uranium enrichment site at Fordo that is deep underground - but only the Americans have the 30,000lb bomb capable of destroying it.

Trump held a meeting on Tuesday with his national security team that lasted nearly 90 minutes in the Situation Room of the White House to discuss their next steps.

According to CBS News, the president's advisers are still divided about how to proceed. The US joining Israel "would completely change" the dynamics of the war, Dara Conduit told BBC News earlier.

Yesterday, Trump took to social media to demand Iran's "unconditional surrender".

Ghoncheh Habibiazad
BBC Persian

More now from Khamenei's remarks.

He says that "wise people who know Iran, its people, and its history never speak to this nation in the language of threats, because Iranians are not those who surrender".

Ghoncheh Habibiazad
BBC Persian

We're now watching a televised statement from Iran's Supreme Leader Ayatollah Ali Khamenei.

It was read out by the presenter, not Khamenei himself.

“Any form of US military intervention will undoubtedly be met with irreparable harm,” the statement says.

We'll bring you more updates as we get them.

Image source, Reuters

Image source, Reuters

Israel's foreign minister Gideon Sa'ar has posted a letter on X that he says he's sent to the head of the UN Security Council and the UN Secretary-General António Guterres.

In it, he explains Israel's rationale for launching its attacks against Iran last week.

He claims the country was given no choice after "decades" of Tehran's "clandestine acts of hostility" and threats by its leaders for Israel's "annihilation".

"It is not merely rhetoric. Iran has a strategic plan to eliminate Israel, which includes concrete plans and actions to achieve this goal," Sa'ar writes.

He also says Israel first struck in what was its "last window of opportunity" to act to thwart a future Iranian attack.

Sa'ar cites the 24 Israeli civilians killed in what he claims have been "indiscriminate" Iranian attacks which deliberately targeted civilians.

Offical figures released by Iran's health ministry said on Sunday that Israel's attacks had killed at least 224 people and says the vast majority of are civilians.

The Israel Defense Forces have confirmed that one of their drones was shot down over Iran.

"During an operational activity, surface-to-air missiles were fired at an Air Force remotely piloted aircraft.

"The device fell in Iranian airspace, there were no casualties and there is no fear of information leaking," an IDF spokesperson said.

Earlier today we reported on Iranian state TV saying that army air defence forces shot down an advanced Hermes drone early this morning in central Isfahan province.

We can't ascertain that the drone mentioned by the IDF is the same one mentioned in Iran, but both descriptions seem to match.

Iranian state television says it will broadcast a message from Supreme Leader Ayatollah Ali Khamenei in a few minutes.

We'll bring you an update on what he says when we have it.

The International Atomic Energy Agency (IAEA) says it has information that two centrifuge production facilities in Iran have been hit.

We heard from Israel earlier that it had struck centrifuge production sites overnight.

The IAEA says that at the Tehran Research Center, one building was hit where advanced centrifuge rotors were manufactured and tested.

At an Iran Centrifuge Technology Company (TESA) site in Karaj, the IAEA says two buildings were destroyed where different centrifuge components were manufactured.

Both sites were previously monitored by the IAEA under the Iran nuclear deal, the international organisation says.

Centrifuges are machines that enrich uranium, which can be used to make fuel for power plants and also nuclear weapons.

As we've been reporting, Israel has carried out further strikes on Iran overnight.

We can bring you footage now from the Iranian Mehr News Agency, which appears to show the country's air defences firing into the sky above Tehran.

The BBC has not independently verified this video, and is unable to report from inside Iran due to restrictions by the country's government, which tightly controls the Iranian media.

It has just gone 12:00 in Israel and 12:30 in Tehran (10:00 BST). If you're just joining us, this is what has happened overnight:

• US President Donald Trump is considering entering the conflict and joining Israel's strikes on Iran. It comes after he called for Iran's "complete surrender" - but he says the US won't kill Iran’s Supreme Leader Ayatollah Ali Khamenei, "at least for now"
• Khamenei responded, saying he will "will never compromise" with Israel
• There were no deaths overnight in Israel from Iranian missile attacks, Middle East regional editor Sebastian Usher reports - Israel says 400 missiles have been fired at it since Friday

• More than 50 Israeli fighter jets conducted operations in Iran overnight, conducting strikes on an Iranian centrifuge facility, a missile production facility near Tehran, and a university linked to Iran's Revolutionary Guards
• Iranian drones and missiles fired toward Israel triggered sirens across the country several times overnight. Iranian media reports Tehran fired Fattah-1 hypersonic missiles toward Tel Aviv

Stay with us as we continue bringing you the latest.

Speaking to BBC 5Live Breakfast a little earlier, political expert Albert Wolf says Trump's demand for "unconditional surrender" from Iran would include a complete end to the country's nuclear programme.

That would be a "humiliation" for them, he says.

Wolf explains that Trump's version of "unconditional surrender" would mean that all of Iran’s nuclear sites are destroyed and its nuclear technology is disposed of.

"They would have to give up their missile programme and end support for the remaining members of the resistance, like Hamas, Hezbollah," he says.

Wolf says this would be hard for Iran because its nuclear programme is a core part of the country's "prestige and status in the world", adding that giving it up wouldn't just be an arms control agreement - but "humiliation".

Later on today, the BBC's experts and correspondents will be answering your questions on the Iran-Israel conflict here on this page and the BBC News channel.

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Nuclear physicist and former UN nuclear inspector David Albright says Iran's underground nuclear facility - Fordo - is 80m (262 feet) below ground and "very difficult to destroy".

Speaking to BBC Radio 5 Live Breakfast, explains that their experiences in Iraq helped the International Inspection Agency of Atomic Energy organisation develop "incredibly good ways of investigating secret programmes".

He adds: “Now that Israel’s striking, I believe Israel can put that site out of operation for a long time. The US could destroy it completely."

Albright, who is also the founder of the Institute for Science and International Security in Washington, says that Fordo is only "one of the more formidable" nuclear sites.

But it isn't the only one, he adds, and so should not be over emphasised.

Fordo was originally built as part of Iran's early 2000s Crash nuclear weapons programme.

Sebastian Usher
Middle East regional editor, reporting from Jerusalem

Image source, EPA

Despite some damage, no people have been reported killed or injured in Israel from the latest overnight volleys of missiles from Iran.

The Israeli government says that approximately 400 ballistic missiles have been fired by Iran since Israel began its attack last Friday, with hundreds of drones also launched.

The Israeli authorities say that since last Friday, there have been around 40 impact sites across the country, 3,800 people evacuated, 24 people killed, and more than 800 injured.

There have been nearly 16,000 claims related to structural damage and more than 1,000 for damage to vehicles.

It does seem that Israel's Iron Dome air defence shield has mostly been working, but at a reported cost of $250m (£186m) a night to operate.

A report in the Washington Post, external quotes a source briefed on US and Israeli intelligence, who says that without resupplies or greater involvement by US forces, Israel may only be able to maintain it for another 10 or 12 days if Iran maintains steady attacks.

Image source, Reuters

You may have seen news this week that Israel had planned to assassinate the supreme leader of Iran, Ayatollah Ali Khamenei, before the US reportedly intervened.

Donald Trump also warned on social media he knows "exactly where the so-called 'Supreme Leader' is hiding."

But who is Khamenei? And why would Israel target him?

Ali Khamenei is Iran's head of state, and has been for more than three decades. His title puts him above the president, Masoud Pezeshkian, as the country's most powerful religious and political leader.

Apart from sweeping powers in governing the country, Khamenei also leads the hardline religious regime that seized control of Iran in the 1979 Islamic revolution.

That was when a popular uprising overthrew Iran's monarchy led by the Shah, Reza Pahlavi, and established a religious republic in its place.

There have only been two supreme leaders since then, both chosen by Iran's Assembly of Experts. The title "Ayatollah" refers to a senior cleric in Shia Islam.

As supreme leader, Khamenei is commander-in-chief of the country's military, which might partly explain why he is seen as a target by Israel.

As Iran is an authoritarian regime, Iranian people have practically no say in choosing their leader. And dissent, including posting criticism of Khamenei on social media, can get you thrown in prison.

Trump's evolving rhetoric about the Israel-Iran conflict suggests he is leaning further towards joining the Israeli offensive, says Professor Amnon Aran, an Israeli foreign policy expert.

Trump posted yesterday on social media Washington's "patience is wearing thin", saying he wants to see an "unconditional surrender" from Tehran.

Aran says that kind of strained language signals he is crossing a threshold, and is "very difficult to row back from," he tells Radio 5 Live.

“All the proclamations and statements by President Trump are reflecting this gradual shift towards a greater inclination to intervene."

“We’re definitely the closest we have been" to a US entry in the conflict since it began, he adds.

Soroush Negahdari
BBC Monitoring

Iranian state TV reports that army air defence forces shot down an advanced Hermes drone early this morning in central Isfahan province.

A correspondent at the scene, standing beside the wreckage, says the drone was intercepted at approximately 05:00 local time (02:30 BST).

He says that the drone was destroyed before it could deploy any weapons, highlighting what he says is the effectiveness of Iran’s early detection and response systems.