Streaks of light in the night sky as Iron Dome interceptors meet rockets launched from Gaza in May 2021. Photo: Getty Images.
During the 11 days of fighting between Israel and Hamas in May 2021, militants in Gaza fired about 4,360 rockets and mortar shells towards Israel. Israel's Iron Dome air defence system did not try to stop all of them. It tracked each launch, ignored rockets heading for open ground, and fired interceptors at those likely to hit towns. The Israeli military said it destroyed about 90% of those threatening rockets, a figure some tallies put even higher. That is the real meaning behind the often-repeated claim that Iron Dome stops "over 90 per cent" of rockets.
Below is a plain explanation of how the system works, where it came from, what it cost, and where its limits lie.
What happened in May 2021
The fighting began on 10 May 2021, after weeks of tension in Jerusalem, and ended with an Egyptian-brokered ceasefire on 21 May. Over that period roughly 3,400 rockets crossed into Israel, about 680 fell short inside Gaza and some 280 landed in the sea, according to figures compiled from Israeli and international sources.
Iron Dome engaged the rockets heading for populated areas, about 1,400 of them by Israeli count, and most were destroyed in the air. A few dozen got through or were missed, causing deaths and damage. In total 13 people were killed in Israel, including two children. In Gaza, Israeli air strikes killed around 260 people, according to the United Nations, including 66 children, with close to 2,000 wounded. The human cost of the conflict fell overwhelmingly on Gaza.
How Iron Dome works, step by step
The interception sequence, from launch detection to the interceptor's explosion. Graphic: BBC, based on information from Rafael Advanced Defense Systems.
Each Iron Dome battery has three main parts that work together in seconds:
- Radar. An EL/M-2084 radar, built by Elta, a subsidiary of Israel Aerospace Industries, detects a rocket shortly after launch and tracks its path.
- Battle management. Software developed by the Israeli firm mPrest calculates where the rocket will land. If the impact point is an empty field or the sea, the system lets it fall. If it is a town, a road or key infrastructure, it orders a launch.
- Interceptors. Launchers, each holding 20 Tamir missiles made by Rafael, fire an interceptor that steers towards the rocket and explodes near it, destroying it in mid-air.
The system is designed for short-range threats, roughly 4 to 70 kilometres away. Batteries are spread around the country and some are mobile, so they can be moved towards areas under heavy fire. Even a successful interception is not perfectly safe: falling fragments can still injure people, which is why Israel's civil defence instructions tell people to stay in shelters until the danger has passed.
Where Iron Dome came from
Israel started work on the system in 2005. The decisive push came after the 2006 war with Hezbollah in Lebanon, when thousands of rockets struck northern Israel, and from years of rocket fire on towns near Gaza such as Sderot. In February 2007 the then defence minister, Amir Peretz, chose Iron Dome as Israel's answer to short-range rockets.
Developed by Rafael Advanced Defense Systems with Israel Aerospace Industries, the system was declared operational in March 2011 and made its first interception of a rocket from Gaza, near Ashkelon, on 7 April 2011. The United States contributed about $1.6 billion towards it between 2011 and 2021, and in 2022 Congress approved a further $1 billion to replenish interceptors used in the May 2021 fighting.
How effective is it really?
Israeli officials credit Iron Dome with saving many lives. Israeli military spokesman Lt Col Jonathan Conricus, quoted by the BBC in May 2021, said casualties would be far higher if it had not been for the Iron Dome system
.
Independent assessment is harder, because detailed data comes mainly from the Israeli military. A few critics, notably the MIT physicist Theodore Postol, have argued that true interception rates are far lower than claimed, based on analysis of videos. Israeli analysts at the Institute for National Security Studies rejected his method as unreliable. Most observers accept that the system intercepts a large share of the rockets it engages, while noting that the headline percentage applies only to that subset.
Limits and criticisms
Cost. Each interception is commonly estimated to cost tens of thousands of dollars or more, with some estimates above $100,000, while a crude rocket can cost a few hundred dollars. Firing selectively helps, but in a long conflict the economics favour the attacker.
Saturation. Large salvos fired at once can overwhelm a battery. Hamas used this tactic in May 2021; on 11 May it said it had fired well over 100 rockets towards Tel Aviv within minutes.
Range of threats. Iron Dome was built for slow, short-range rockets and mortars. Longer-range and ballistic missiles are handled by other layers of Israel's air defence, such as David's Sling and the Arrow system.
Political effects. Some analysts argue that because Iron Dome reduces Israeli casualties, it lowers pressure on all sides to address the underlying conflict. Others say it gives Israeli leaders more time and room to avoid escalating to a ground war.
Where Hamas rockets come from
Rockets fired from Gaza are a mix of types, from small homemade Qassam rockets to longer-range models able to reach Tel Aviv, Jerusalem and beyond. Many are now assembled inside Gaza, from parts that were smuggled in, often through tunnels from Egypt, or made from scavenged materials. Israel says Iran has supplied Hamas and Palestinian Islamic Jihad with money, know-how and training for rocket production. Iran has openly expressed support for these groups, though it has denied some specific accusations.
Israel's longer-term hope, expressed after the 2020 normalisation agreements with several Arab states, was that wider regional recognition would reduce outside support for armed groups in Gaza. Events since then have shown how far that hope was from being fulfilled, and Iron Dome has remained a central part of Israel's defence in every round of fighting since.
Sources: Wikipedia: Iron Dome; Wikipedia: 2021 Israel–Palestine crisis; original reporting and graphic by the BBC; photo by Getty Images.
COMMENTS