Tensions are high along Israel's border with Lebanon, where Israeli forces have been trading fire with the militia group Hezbollah. In a speech last week, Hezbollah's leader warned that if war erupts, then all of Israel would be under threat.
"The enemy knows very well that no place will be safe from our missiles and drones," Hezbollah's leader, Hassan Nasrallah, said on June 19.
Keeping those weapons from hitting Israeli territory is the job of a sophisticated air defense system called Iron Dome. It has intercepted thousands of missiles over the years, and it has been critical to protecting Israel's cities during the latest war in Gaza.
But some experts warn that Hezbollah's arsenal could push the system past its limits.
The Iranian-backed group has been conducting increasingly brazen attacks using exploding drones and low-flying missiles that Iron Dome has struggled to intercept. And last week, Hezbollah published a 10-minute-long surveillance video from an unmanned aerial vehicle that had slipped past multiple Iron Dome launchers. Among the sensitive locations it filmed was a secure manufacturing facility belonging to the Israeli defense firm Rafael — the company that makes the missile defense system.
The implication was clear: Hezbollah has Iron Dome in its sights. And this could be just a small taste of what's to come, says Tom Karako, director of the Missile Defense Project at the Center for Strategic and International Studies. Unlike the Palestinian group Hamas, Hezbollah is believed to have a large arsenal of precision-guided weapons that it could fire in a war with Israel.
"Look, there's not enough Iron Domes in the world to contend with the reported 100,000 or so rockets that Hezbollah may have," he warns.
A miraculous shield
Iron Dome was first deployed in 2011, and it has become iconic in Israeli society. The system is made up of three components: a high-powered radar system, a targeting computer and interceptor missiles.
Iron Dome uses its radar to detect incoming rockets. Its targeting computer is able to respond extremely quickly, calculating not just where an incoming rocket is but where it's going to land. If the rocket is likely to hit an open area, then the missile system won't fire — but if it's headed for a populated area, then Iron Dome will launch interceptors.
The interceptors can fly quickly to the path of the incoming rocket, where they explode, sending shrapnel into the target.
Karako says that Iron Dome works not because it's state-of-the-art but because it's economical. The interceptor missiles are relatively affordable, and they're fired only if they're really needed. "They prioritized being choosy about the shots that they take, and they prioritized cost," he says.
The system boasts a more than 90% success rate, according to its manufacturer. And its performance has astounded even the experts. During a 2021 conflict, Palestinian militant groups fired hundreds of rockets from the Gaza Strip toward Tel Aviv, Israel.
Some of the rockets got through, killing a handful of civilians, but many more were intercepted. Yehoshua Kalisky was on a highway in Tel Aviv when a barrage came in. He watched as Iron Dome interceptors flew up and struck the incoming rockets.
"I lay down and looked at the sky, and it was like a miracle — every missile that came was shot down," he says.
Kalisky is a senior researcher at the Institute for National Security Studies in Tel Aviv and an expert on missile defense. He says much of Iron Dome's success in Gaza comes down to its radar. "It has an excellent radar system — very fast, very accurate — and it's all automatic," he says.
Gaps in the dome
But Kalisky has been watching as the system has struggled to deal with Hezbollah's tactics. The group has been using anti-tank missiles, which fly low to the ground. The missiles, which can be fired only over short ranges, are too fast for Iron Dome to intercept, and they fly below the minimum altitude of the interceptor missiles.
Unmanned aerial vehicles (UAVs) also pose a problem for Iron Dome's radar, Kalisky says: The UAVs are made of carbon-based materials like wood and plastic that don't reflect radar as well as metal rockets do. "It's very difficult to detect them." Moreover, the border with Lebanon is home to a lot of birds that can be mistaken by the radar system for UAVs. "You have many, many false alarms," he says.
"To be honest, I think that Hezbollah recognized our gaps," says Zvika Haimovich, a retired brigadier general who oversaw Israel's air defenses from 2015 to 2018. "For that reason, they are using more and more UAVs in the last few weeks."
Haimovich says that a conflict with Hezbollah will look nothing like the previous wars with Gaza, including the one that began on Oct. 7. "Hezbollah holds today double and triple the number of rockets and missiles that Hamas launched on Oct. 7," he says.
In fact, the exact size and composition of Hezbollah's arsenal is a closely guarded secret. "We often see numbers like 150,000 or even 200,000 [rockets]," says Fabian Hinz, an expert on Middle Eastern missile arsenals at the International Institute for Strategic Studies in Berlin. "It's a bit difficult to say how serious these assessments are ... but in general we can say that these are quite massive stockpiles."
Many of Hezbollah's rockets are unguided, short-range systems, but the group also has more sophisticated weapons, Hinz says. "I would say one major, major difference between Hamas and Hezbollah is that Hezbollah has precision-guided weaponry," Hinz says.
Those weapons can threaten Iron Dome in another way, he says: by attacking the missile launchers themselves.
"If you know where the Iron Dome [missile] batteries sit, you might actually try taking out the batteries themselves," he says. In fact, Hezbollah published video of an apparent strike on an Iron Dome launcher in June, though it's unclear whether it was a real system or a decoy.
Haimovich says that Iron Dome could still provide protection. It will likely fare better against some of Hezbollah's longer-range missiles because they fly high and are easier to intercept. In April, Iron Dome and other Israeli and U.S. missile defense systems were largely able to fend off a volley of high-flying ballistic missiles fired by Iran.
Buying time
A new conflict in Lebanon would challenge Iron Dome in another way: Israel doesn't have an infinite number of interceptor missiles in its stockpile. Haimovich says that since Oct. 7, Israel has fended off attacks from every direction. As it has done so, it has been expending missiles faster than they can be manufactured.
"After eight months of thousands of interceptions, it's a big challenge," he says.
Karako says that if there is a broader war with Hezbollah, it's unlikely that Iron Dome can provide the kind of protection that Israelis have grown accustomed to.
But, he adds, that's not surprising. The reality is that no magical shield can protect citizens forever.
"Air defense buys time — buys decision-makers time to end the conflict by other means," he says.
But, he adds, "just because you buy time doesn't guarantee that decision-makers will make good decisions."
NPR's Itay Stern contributed to this report.
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