Shrouded in secrecy. Never confirmed or denied by the government. This is Israel’s alleged nuclear weapons programme.

Israeli Prime Minister Benjamin Netanyahu has long warned that Iran’s nuclear research is secretly looking to develop a nuclear bomb – something Iran has repeatedly denied.

But for decades there have been suspicions that Israel, not Iran, is the first Middle East country to obtain a nuclear weapon.

“It’s very opaque, there’s very little detailed information about it,” says Professor Nick Ritchie, an expert on international security and nuclear proliferation at the University of York.

But he adds: “There’s no debating whether Israel has nuclear weapons and a nuclear weapons programme. Everybody knows it does.”

When did Israel supposedly get nuclear weapons?

It’s believed Israel began building a stockpile of nuclear weapons in the early 1960s, according to a research document for the UK parliament.

“Israel developed nuclear weapons because of fear of encirclement and attack by the Arab states, potentially supported by the Soviet Union, that opposed its existence,” Prof Ritchie tells Sky News.

“There was a sense of acute threat to the existence of the Jewish state after the Holocaust. Back then it was not the regional power that it is now.”

In a declassified memo to President Richard Nixon in 1969, US Secretary of State Henry Kissinger discussed the recent purchase by Israel of American Phantom fighter aircraft – which were capable of carrying nuclear weapons.

He told the president that Israel had committed “not to be the first to introduce nuclear weapons” to the Middle East.

Kissinger added: “But it was plain from the discussion that they interpreted that to mean they could possess nuclear weapons as long as they did not test, deploy, or make them public.”

Whistleblower describes working at Israeli nuclear reactor

In the late 1980s, an Israeli former nuclear technician revealed information about his work at Israel’s Dimona reactor to a British newspaper, which led foreign experts to conclude that Israel had produced enough material for up to 200 nuclear warheads.

Mordechai Vanunu was later kidnapped by Mossad and brought back to Israel, where he was sentenced to 18 years in prison, the UK parliament document said.

When asked on CNN in 2011 whether his country has nuclear weapons, Mr Netanyahu responded: “Well, we have a longstanding policy that we won’t be the first to introduce nuclear weapons into the Middle East, and that hasn’t changed.”

Prof Ritchie says: “Senior Israeli officials, including prime ministers such as Ehud Barak, have acknowledged that Israel has a nuclear weapons programme, more often when they have retired.”

While it has repeatedly criticised Iran for what it claims is a pursuit of nuclear weapons, Israel itself is not signed up to the Nuclear Non-Proliferation Treaty, which commits countries that don’t have nuclear arms not to build or obtain them.

Read more:
What we know about Iran’s secretive ‘nuclear mountain’
Even after US strikes, Iran may still be able to make a nuclear bomb

What nuclear weapons might Israel have?

Given Israel’s policy of ambiguity in relation to its alleged nuclear weapons programme, it’s hard to precisely estimate how many nuclear warheads it may possess – and what type.

The Stockholm International Peace Research Institute (SIPRI), an independent organisation that provides analysis about conflict, says Israel likely has 90 warheads and they are made from plutonium.

Prof Ritchie says it is difficult to be certain but it is believed Israel has fission-based nuclear weapons – like the kind dropped on Hiroshima and Nagasaki by the US.

Whether they have thermonuclear fusion weapons – more powerful bombs like those in the arsenals of the US, Russia and the UK – is “difficult to say with certainty”.

“But of course Israel is a very geographically small state,” Prof Ritchie says, adding that in the event of an existential attack on the country, any use of its nuclear weapons against the armed forces of attackers in the region could result in Israel facing “extensive fallout” from the blasts.

How would Israel launch any potential nuclear attack?

There is the question of how Israel would deliver any nuclear strike.

The UK parliament document says: “Based on unconfirmed reports, Israel could be in possession of the nuclear triad, making it capable of delivering a nuclear capability via land, air and/or sea.”

The IDF operates several planes that could be capable of launching nuclear weapons, including the American-made F-16 and F-35 fighter jets.

Around 30 of Israel’s nuclear warheads are estimated to be gravity bombs (unguided munitions dropped from aircraft) for delivery by fighter jets, SIPRI has said.

It also reportedly has the ground-launched Jericho ballistic missile family, reportedly with ranges that could exceed 5,500km (3,400 miles), according to the UK parliament document.

It’s thought that up to 50 nuclear warheads are assigned for land-based missile delivery, SIPRI said.

The Israeli government has never confirmed that it possesses Jericho missiles.

Finally, Israel operates five Dolphin-class submarines which may also be capable of carrying nuclear warheads.

“Given that Israel does not officially acknowledge its apparent possession of nuclear weapons, the circumstances under which it would use them are highly unclear,” SIPRI said.

Debate over nuclear weapons

👉Listen to The World with Richard Engel and Yalda Hakim on your podcast app👈

Discussion of Israel’s alleged nuclear weapons programme raises questions about which countries – if any – should possess them and how this is enforced.

“The argument that nuclear weapons are acceptable for Israel but not for other states in the region is widely viewed as Western hypocrisy that is difficult for a number of countries to accept,” says Prof Ritchie.

“If it’s not acceptable for Iran to have nuclear weapons, why is it acceptable for Israel to have them? This is why many countries in the region, like Egypt, have pushed for the negotiation of a treaty to ban all weapons of mass destruction in the region, covering chemical, biological and nuclear weapons.”

Sky News has approached the Israeli government for comment.

It would be sensible to wait until the dust has settled before judging whether the US strikes on Iran were, in Donald Trump’s, words, “a spectacular military success”.

And when dropping bombs that weigh more than 13 tonnes each, there’s going to be a lot of dust.

The Pentagon says the operation against Iran’s three largest nuclear facilities involved 125 military aircraft, warships and submarines, including the largest operational strike by B2 bombers in history.

Follow latest: Iran considering ‘all options’ after US strikes

The B-2s dropped 14 of America’s most powerful GBU-57 “bunker buster” bombs on the Natanz uranium enrichment plant and Iran’s most sophisticated nuclear facility at Fordow.

The first time, according to the Pentagon, the weapons have been used in a military operation.

The Fordow complex, buried deep in a mountain, was the only site not previously damaged by Israeli strikes over the last few days.

The use of multiple GBU-57 bombs at Fordow is telling.

Despite their size, it was known that one of them would be insufficient to penetrate 80+ metres of solid rock believed to shelter Iran’s most sophisticated uranium enrichment technology deep within Fordow.

Read more:
Fordow: What we know about Iran’s secretive ‘nuclear mountain’
What we know so far about US strikes on Iran’s nuclear facilities

Satellite images reveal three visible holes at two different strike points on the mountainside above the complex.

The sites appear to be close to what may have been ventilation shafts – possibly chosen to maximise damage below and render the facility useless.

Using several of the bombs in the same location is likely designed to allow each to penetrate further than the first before detonating.

If nuclear facilities at Isfahan, Natanz and Fordow were destroyed – as the US claims – or even crippled, it would certainly halt Iran’s ability to enrich the Uranium needed to make a viable nuclear weapon.

But that’s not the same as preventing Iran’s ability to make a nuclear bomb. To do that, they need “weapons-grade” uranium; the necessary metal-shaping, explosives and timing technology needed to trigger nuclear fission in the bomb; and a mechanism for delivering it.

The facilities targeted in the US raid are dedicated to achieving the first objective. Taking naturally occurring uranium ore, which contains around 0.7% uranium 235 – the isotope needed for nuclear fission – and concentrating it.

The centrifuges you hear about are the tools needed to enrich U-235 to the 90% purity needed for a compact “implosion”-type warhead that can be delivered by a missile.

And the reality is Iran’s centrifuges have been spinning for a long time.

United Nations nuclear inspectors warned in May that Iran had at least 408kg of uranium “enriched” to 60%.

Getting to that level represents 90% of the time and effort to get to 90% U-235. And those 400kg would yield enough of that weapons-grade uranium to make nine nuclear weapons, the inspectors concluded.

The second element is something Iran has also been working on for two decades.

Precisely shaping uranium metal and making shaped explosive charges to crush it in the right way to achieve “criticality”, the spark for the sub-atomic chain reaction that releases the terrifying energy in a nuclear explosion.

In its recent bombing campaign, Israel is thought to have targeted facilities where Iranian nuclear scientists were doing some of that work.

Analysis on the US strikes:
Trump’s two big gambles as US enters war with Iran
For Trump, the performative presidency just got real

But unlike the industrial processes needed to enrich uranium, these later steps can be carried out in laboratory-sized facilities. Easier to pack up and move, and easier to hide from prying eyes.

Given that it’s understood Iran already moved enriched uranium out of Fordow ahead of the US strike, it’s far from certain that Iran has, in fact, lost its ability to make a bomb.

And while the strikes may have delayed the logistics, it’s possible they’ve emboldened a threatened Iran to intensify its warhead-making capability if it does still have one.

Making a more compact implosion-based warhead is not easy. There is debate among experts about how advanced Iran is along that road.

But if it felt sufficiently motivated, it does have other, less sophisticated nuclear options.

Even 60% enriched uranium, of which – remember – it has a lot, can be coaxed to criticality in a much larger, cruder nuclear device.

Follow The World

Listen to The World with Richard Engel and Yalda Hakim every Wednesday

Tap to follow

This wouldn’t pose as much threat to its enemies, as it would be too heavy to fit on even the best of Iran’s long-range missiles.

But it would, nonetheless, elevate Iran to the status of a nuclear power.

There is much that is still not known about the US strikes against Iran’s nuclear facilities.

Reports are coming in about which sites were hit and what military elements were involved, as President Donald Trump hails the attack on social media.

Here’s what we know so far.

Follow latest: US bombers strike three Iranian nuclear sites

Which sites were hit?

America appears to have hit the three key locations in Iran’s nuclear programme.

They include Isfahan, the location of a significant research base, as well as uranium enrichment facilities at Natanz and Fordow.

Natanz was believed to have been previously damaged in Israeli strikes after bombs disrupted power to the centrifuge hall, possibly destroying the machines indirectly.

However the facility at Fordow, which is buried around 80 metres below a mountain, had previously escaped major damage.

Details about the damage in the US strikes is not yet known, although Mr Trump said the three sites had been “obliterated”.

Read more:
Fordow: What we know about Iran’s secretive ‘nuclear mountain’

What weapons were used in the attacks?

The White House and Pentagon did not immediately elaborate on the operation, but a US official said B-2 heavy bombers were involved.

Fox News host Sean Hannity said he had spoken with the president and that six bunker buster bombs were used on the Fordow facility.

Bunker buster bombs are designed to explode twice. Once to breach the ground surface and again once the bomb has burrowed down to a certain depth.

Israel has some in its arsenal but does not have the much more powerful GBU-57, which can only be launched from the B-2 bomber and was believed to be the only bomb capable of breaching Fordow.

Hannity said 30 Tomahawk missiles fired by US submarines 400 miles away struck the Iranian nuclear sites of Natanz and Isfahan.