Amid spiraling violence sparked by clashes in Jerusalem, a familiar sound has returned to southern Israel: the blare of rocket sirens and the explosions of Iron Dome interceptors.

While the back and forth of Palestinian rockets being largely disabled by Israel’s widely lauded missile defense system, and subsequent Israeli airstrikes on Gaza, is routine, the current round of conflict is unusually intense.

Since violence between Israel and Palestinians began to escalate on Monday, hundreds of rockets have been fired from the Gaza Strip, killing at least six Israelis. On Tuesday, Hamas launched a volley of rockets at Tel Aviv, Israel’s largest city, after it said a high-rise building in Gaza was destroyed by an Israeli airstrike.

Israeli airstrikes in the Gaza Strip have killed at least 48 people, including 14 children, according to Palestinian officials.

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.

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.

Sirens sounded in Ashkelon, Israel as the Iron Dome defense system intercepted several missiles fired at the city from the Gaza Strip early on May 11. (The Washington Post)

Speaking to Israel Hayom this week, 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,” including “threats that don’t even exist in the field at this time, but will probably emerge in the coming months.”

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

“Over 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.

“No 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.

On Tuesday, the Israeli military again said that 90 percent of rockets that reached Israeli airspace were destroyed by Iron Dome. More than 1,000 rockets had been fired from Gaza since the start of the conflict, per the Israeli military.

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 fires 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 on Tuesday after his building was struck by a rocket. “We can only rely on the Iron Dome and luck.”

On Tuesday evening, Hamas fired 130 rockets at Tel Aviv in what it said was a response to Israel’s destruction of the high-rise building in Gaza during dozens of airstrikes in the small area.

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, like those that hit Tel Aviv, roughly 40 miles from the Gazan border, on Tuesday, 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.

Israel had already seen rockets fired toward Jerusalem on Monday, one of which damaged a house in a southwestern suburb, but officials were surprised at the number of long-range rockets that have since reached Tel Aviv.

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 is now a fellow with the Washington Institute, told The Post in 2019.

The Israeli military instructed all residents, including farmers, living within that distance from Gaza to temporarily remain in their homes out of concern on Wednesday morning.

Though the weapons 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 around $80,000, according to reports in the Israeli press.

This report has been updated.

correction

A previous version of this article gave the incorrect year for a threat assessment by Michael Armstrong. It was written in 2019, not 2018. The article has been corrected.