The Washington PostDemocracy Dies in Darkness

Here’s how rockets from Gaza test Israel’s Iron Dome

Israel's Iron Dome air defense system intercepts rockets launched from the Gaza Strip on Wednesday. The Israeli military said it renewed strikes on Gaza, killing one person, according to the Palestinian territory's Health Ministry. (Menahem Kahana/AFP/Getty Images)
7 min

A familiar sound has returned to southern Israel: the blare of rocket sirens and the explosions of Iron Dome interceptors. Palestinian militants in the Gaza Strip launched hundreds of rockets into Israel on Wednesday, following a spate of Israeli airstrikes.

Israel’s missile defense system disabled 60 of 270 rockets fired by Gaza militants on Wednesday, Israel Defense Forces (IDF) said. Three landed in populated areas, the Times of Israel reported, with the rest failing to launch in Gaza or falling in open areas.

The rocket attacks followed Israeli airstrikes that killed more than 20 people in Gaza over two days. They are the first to target Tel Aviv, the country’s most populous city, since a two-week outbreak of violence in 2021.

With rocket fire and airstrikes continuing, here’s what you need to know about the rockets fired from Gaza and the Israeli air defense network intercepting them.

Rockets launched from Gaza in retaliation for Israeli airstrikes that killed over a dozen people are intercepted by Israel’s Iron Dome on May 10. (Video: Channel 13)

What is Iron Dome?

Israel’s Iron Dome is an air defense system developed by the Israeli firms Rafael Advanced Defense Systems and Israel Aerospace Industries, with financial and technical support from the United States.

First put into service in 2011, it is designed to stop short-range rockets and artillery like those fired from Gaza. Two separate systems, known as David’s Sling and Arrow, are designed for medium- and long-range threats, including planes, drones, rockets and missiles.

Iron Dome relies on a system of radar and analysis to determine whether an incoming rocket is a threat, firing an interceptor only if the incoming rocket risks hitting a populated area or important infrastructure.

The interceptors, which are fired vertically either from mobile units or a static launch site, are designed to detonate the incoming rocket in the air, producing the explosions in the sky that have come to accompany warning sirens during recent Israeli-Palestinian conflicts.

Speaking to Israel Hayom in 2021, defense officials said that the hardware had not changed since the system was first deployed, but that software changes had made the system more capable as the years went by.

Moshe Patel, director of the Defense Ministry’s Homa directorate, told the right-wing newspaper that Iron Dome had the “ability to counter cruise missiles, drones and more.”

But some critics of Iron Dome have long said it fundamentally serves to prolong conflict.

“[O]ver time, Iron Dome may do them more harm than good,” Israeli political scientist Yoav Fromer wrote in The Washington Post in 2014. “… Iron Dome’s ability to protect Israelis from periodic rocket attacks so far will never remove the strife and discontent that has produced the motivation to ruthlessly fire them in the first place.”

How successful is it at stopping attacks?

Israeli officials and defense companies say that the system has stopped thousands of rockets and artillery from hitting their targets, with a success rate of more than 90 percent.

However, some defense analysts question those numbers, arguing that the Israeli figures for successful interception are unreliable and that groups including Hamas and Islamic Jihad that fire rockets and artillery from Gaza have adapted to the system.

“[N]o missile defense system is perfectly reliable, especially against an evolving threat,” Michael Armstrong, an associate professor at Brock University who has studied the system’s effectiveness, wrote in a 2019 assessment for the National Interest.

During clashes in May 2021, the Israeli military again said that 90 percent of rockets that reached Israeli airspace were destroyed by Iron Dome. More than 1,000 rockets were fired from Gaza over 38 hours, per the Israeli military. In August 2022, the IDF put the Iron Dome’s interception success rate at 97 percent, the Times of Israel reported.

But the rate of interceptions dropped to 60 percent during a burst of rockets from Gaza on an afternoon last week, the Jerusalem Post reported. A preliminary IDF investigation found that a technical defect had allowed a “small number” of rockets through, the newspaper reported. It was quickly corrected and the system’s effectiveness restored, the probe concluded.

The country again touted the system on Wednesday, with its official account on Twitter sharing footage of rockets being intercepted and writing, “Thank God for the Iron Dome.”

“Last week’s technical difficulties were isolated incidents and the IDF’s Aerial Defense Array maintains a high level of operational readiness and performance,” read a statement from the IDF, sent by email Thursday.

Iron Dome has changed life for many Israelis during recent conflicts, allowing a degree of normality in southern parts of the country that were once under the heavy shadow of rocket strikes.

Supporters of the Iron Dome system have said that it has stopped the need for Israel to send in troops to Gaza during times of conflict, as it had done during 2008 and 2009.

The system’s comparatively low cost — because it is designed to fire only on threats to human life or infrastructure, fewer interceptors are needed — also makes it attractive to foreign governments, including the U.S. Army, which has bought two batteries itself.

But some Israelis say the government relies too much on the system and does not put enough resources into other defenses, including shelters.

“The house is not protected, and it is not realistic to get to the neighborhood shelters, especially when the barrages are so continuous,” Guy Mann, a resident in Ashkelon, told Israel’s Army Radio in 2021 after a nearby building was struck by a rocket. “We can only rely on the Iron Dome and luck.”

What rockets are fired from Gaza, and what problems do they pose for Iron Dome?

Though Iron Dome has been in use for a decade, rockets are still fired into Israel during times of tension with Palestinian groups. Even at the upper estimates of Iron Dome’s success rate, some can get through to populated areas.

Experts who track the arsenals of Hamas and Islamic Jihad estimate that the groups may have tens of thousands of rockets, often made with little more than explosives and metal casing.

Hamas and Islamic Jihad, both designated terrorist groups by the United States, were initially aided by advisers from Iran and other allies with supplies smuggled over the Egyptian border. However, much of the work can now be done domestically by Palestinian experts.

Hamas, which now controls Gaza, began producing a rocket called Qassam in about 2001, during the second intifada. At first, the rockets had a range of just two or three miles, but later versions, such as the “Qassam 3,” have a range of about 10 miles.

But some rockets have a considerably longer range. The Israeli military said in 2019 that a Palestinian rocket that hit a house near Tel Aviv had a range of 75 miles.

Short-range rockets are also a threat because Iron Dome is less effective at ranges of 2.5 miles or less, Michael Herzog, a retired brigadier general in the Israel Defense Forces who was appointed the Israeli ambassador to the United States in November 2021, told The Post in 2019.

On Wednesday, air raid sirens sounded across central Israel, going as far north as Tel Aviv to warn of the rocket attacks, sending some civilians running for shelters, IDF said. The Israeli Defense Ministry sought cabinet permission to expand a state of emergency to encompass Tel Aviv and Jerusalem.

Though the rockets are often crude and many lacked guidance systems, their sheer numbers and low cost are an advantage against Iron Dome. While a rocket may cost as little as a few hundred dollars, each interceptor costs about $80,000, according to reports in the Israeli press.