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 Revolutionary Guards, Hossein Salami. 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 could last for days. How might an Iranian assault test Israel’s defences over the coming days or weeks?

What is the Iron Dome?

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 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.

According to the Centre for Strategic and International Studies (CSIS), 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. 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 Iron Dome work?

In essence, when a short-range 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.

Today, the Iron Dome consists of at least 10 sites in Israel that form a shield against the common types of projectiles its neighbours have used to threaten it. Each site is called a “battery” and includes three components: 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.”

The system can down rockets launched from between four and 70 kilometres away (roughly the distance from, say, Lebanon’s south to Haifa, or from Gaza to Tel Aviv.) 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.”

Israeli company Rafael Advanced Defence Systems says the Iron Dome has a 90 per cent interception rate. “It has proven extremely effective since last year since the Hamas attacks,” says Shoebridge. Still, some rockets fired by Hezbollah across the Blue Line – the de facto border between Lebanon and Israel – have not been caught.

The Iron Dome is not Israel’s only missile defence system – “it’s the poster child,” says Shoebridge – instead forming part of a layered approach. Israel defends itself against potential long-range ballistic missile attacks with “Arrow 3”, capable of shooting down missiles from as high as space, while “Arrow 2” protects against medium-range missiles fired through the upper atmosphere. The Arrow system uses 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.”

Another layer is David’s Sling, capable of intercepting missiles from 40 to 300 kilometres away. It is designed to spot ballistic missiles, cruise missiles, aircraft and drones. Israel had rarely used the system before the Gaza War – and has used it sparingly since, including to shoot down several Hamas projectiles aimed at Tel Aviv and Jerusalem in 2023. In September, it also intercepted a Qadr 1 ballistic missile launched from Lebanon towards the headquarters of Israeli intelligence agency Mossad in Tel Aviv, a high-value target that Hezbollah deemed “responsible for the assassination of leaders and the explosion of pagers and wireless devices”.

The IDF also has radar-directed cannon and machineguns 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.”

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 during its attack in October 2024.

Can attacking rockets overwhelm the Iron Dome?

Most of Iran’s missiles were blocked by Israel’s broader missile-defence system, which also deal with projectiles that are more powerful than just rockets and drones. However, the deadly October 7 attack on Israel in 2023 showed that the system could be penetrated. Hamas-led militants fired an estimated 3500 projectiles from Gaza on that day, most in a short timeframe, providing cover for the trucks, motorbikes and even a paraglider they used to cross into Israel where they killed nearly 1200 people.

The Iron Dome layer has a saturation point, although that point is not publicly known. Iran is estimated to have thousands of ballistic missiles – which travel at high parabolic trajectories – as well as cruise missiles that can travel at a lower altitude. In an attack on Israel in April 2024, it also used more than 100 drones.

Too many rockets approaching is one way a missile defence system can be overwhelmed, or the Israelis could simply run out of interception missiles. Since Iran’s attacks on Israel in 2024, Israel has had the opportunity to learn how to position its Iron Dome and its other missile defence systems to deflect Iranian attacks, says Ben Zala from Monash University. “They [Israel] will be activating all of their intelligence and military assets around the region to be ready for whatever the Iranian response is,” he says. “The Israelis will be expecting a response, and they will be expecting a fairly robust response. None of this will be a surprise to them when it comes.”

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

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