For more than a decade, Israel’s so-called Iron Dome missile defence system has been in action, and has intercepted thousands of rockets lobbed by militants from neighbouring areas. Now the spotlight has swung to Iran, which is responding to Israeli airstrikes on its nation.

On Friday, Israel hit several Iranian nuclear facilities and ballistic missile factories – as well as killing top nuclear scientists and military officials, including the leader of Iran’s Islamic Revolutionary Guard. Iran retaliated by launching a wave of missiles at Israel, with footage showing some striking residential buildings in Tel Aviv and others being intercepted by the Iron Dome. The attacks and counter-attacks continue.

How might an Iranian assault test Israel’s defences, commonly known as the Iron Dome, over the coming days or weeks?

What is the Iron Dome?

When a missile, rocket or drone hurtles towards Israel, a sophisticated system on the ground works out whether to counter the incoming projectile with its own missile or not. It is designed to ignore those that don’t pose an obvious threat.

Often, this whole system is referred to as the “Iron Dome” as a handy shorthand. Technically, however, the Iron Dome is the name of just one of Israel’s layers of missile defence, which include other systems called “Arrow” – capable of shooting missiles in space – and “David’s Sling”, a versatile system designed to target ballistic missiles, cruise missiles, aircraft and drones. Which assets are deployed when depend on the particular threat. “In these circumstances, you would imagine they’d be throwing everything they can at the incoming warheads,” says James Dwyer, an expert on ballistic missile defence technology at the University of Tasmania.

Israeli efforts to develop a missile shield go back four decades. In 1986, Israel and the United States signed a memorandum of understanding to develop missile defence, tied to US president Ronald Reagan’s Strategic Defence Initiative (known as Star Wars).

Efforts were stepped up in 1991 when Iraq fired conventionally armed Scud missiles at Israel during the Gulf War, according to Peter Dombrowski and Catherine McArdle Kelleher in a 2013 analysis. “Since then, Israel and the United States have co-operated on several missile-defence programs, including joint technology development, industrial co-operation, and a program of testing and exercises in addition to shared funding,” they write. “Far more than the United States, Israel sees its adversaries’ air and missile capabilities (including conventionally armed ballistic missiles) as part of a continuous spectrum of threats to its population and forces.” (In January, Donald Trump made an executive order calling for what he described as an “Iron Dome for America”, a project now tagged the Golden Dome.)

Israel began work on a system it called the Iron Dome after its 34-day war with Lebanon in 2006. Its first mobile battery (more on them in a moment) was rolled out in March 2011 on the outskirts of Beersheba, a town in southern Israel, after a bout of rocket attacks by militants in Gaza. In April of that year, the IDF said it had used the Iron Dome to intercept its first missile, a rocket from Gaza targeting the coastal city of Ashkelon.

The Iron Dome was further developed with assistance from the United States between 2012 and the 2014 Gaza conflict, by which time nine batteries were operational, according to the Centre for Strategic and International Studies (CSIS). CSIS reports that during that conflict some 4500 rockets and mortars were launched into Israel; about 800 were identified as a threat to life; 735 were successfully intercepted.

How does the whole missile defence system work?

The Iron Dome component has to date largely been used to form a shield against the common types of basic unguided projectiles launched from Israel’s immediate neighbours, such as rockets fired from Hamas in Gaza and Hezbollah in Lebanon. It is believed to consist of 10 mobile batteries, each made up of three essential parts: radars; three or four launchers, each holding 20 interceptor missiles; and a manned control centre from where defence personnel oversee interceptions.

“What humans do is analyse the attack profile that’s coming in and then, essentially, work out how best to counter it,” says Malcolm Davis, a senior analyst at the Australian Strategic Policy Institute. “And then the Iron Dome System is automated, in the sense that you’re not having humans launching individual missiles.”

“You’ve got a missile coming at high speed – you’ve got to be able to hit a bullet with a bullet, basically.”

For shorter-range attacks, the process from radar detection to interception can take less than 30 seconds, says Iain Boyd, director of the Centre for National Security Initiatives at the University of Colorado.

One of the system’s strengths is its mobility. “It’s not a fixed thing,” says Michael Shoebridge, director of Strategic Analysis Australia. “You can relocate the systems and position them if the threat changes. It also means as far as targeting them to destroy them, that’s harder because they can move.”

While the Iron Dome is designed to target threats within Israeli airspace, other layers of defence are designed to reach out and intercept weapons much further away, such as the ballistic missiles fired by Iran, which can travel high, even into space, before plummeting to Earth. “It’s only a few years ago that people were saying it was technically impossible to shoot down high-speed missiles,” says Shoebridge. “And ballistic missiles are some of the highest-speed missiles on the planet because they go up into the atmosphere and then come down at enormous velocity.”

The Arrow 3 missile defence system is reportedly capable of shooting down missiles outside the atmosphere, while the Arrow 2 protects against medium-range missiles raining down from the upper atmosphere.

The Arrow system uses both radar and satellite technology, says Davis. “If they detect an Iranian missile being launched, they would immediately get a notification from the satellite that would then give them a missile tracker.” Once a ballistic missile attack is detected, the entire system might team up to defeat it, with the Arrow defences attempting to engage the threat well outside Israeli airspace. David’s Sling and, as a last resort, Iron Dome might be tasked with intercepting any missiles that slip through the net.

“They’re able to intercept all the way down with the various layers of defence,” says Dwyer. “Which is why you’ll see some intercepts almost at the last second. You want to avoid that if possible because you’re still going to have debris falling and there’s the risk that you might actually still have a live warhead tumble out of control.”

The IDF also has radar-directed cannon and machine guns to deploy against short-range rockets and drones. “They’re like multiple umbrellas,” Shoebridge says of the overall system. “Each umbrella can be porous, and that’s why you need multiple layers.”

Moreover, says Shoebridge, Israel has been actively targeting Iran’s ability to launch missiles and drones in the first place. “It’s not just passively receiving and defeating incoming missiles or drones, it’s stopping them being put on launchers,” he says. “They’re trying to destroy Iranian stockpiles and storage areas for missiles and drones and manufacturing for them. The best defence is to never have the missile launch towards you.”

Israel’s allies also provide another layer of defence. A spokesman for the US Pentagon said two US Navy destroyers fired about a dozen interceptor missiles to down Iranian projectiles when Iran launched about 200 ballistic missiles against Israel in October 2024, a massive escalation between the two countries which followed Israel’s assassination of a Hamas leader on Iranian soil (using a remotely detonated explosive device hidden in his room, according to The New York Times).

Can attacking rockets overwhelm Israel’s defences?

While Israel has apparently been successful in countering many of Iran’s recent attacks, “the Iranians have been getting missiles through,” says Malcolm Davis. He suggests the sheer quantity of Iranian attacks means one or two will succeed. “Missile defence is an incredibly difficult task to do, in terms of targeting,” he says. “You’ve got a missile coming at high speed – you’ve got to be able to hit a bullet with a bullet, basically.”

So how has the system performed overall? “As far as we can go, the whole thing has been working quite well,” says Dwyer. “Obviously, there has been some leakage with missiles getting past, but that’s kind of to be expected. Ballistic missiles travel so fast.”

Many lives have likely been saved, says Davis. In addition, “I think the lessons being learned from this will improve ballistic missile defence capabilities going forward, gathering valuable data on what works and what doesn’t.”

This Explainer was first published in 2024 and has since been updated.

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