How Israel's Iron Dome Defense System Works

The American defense company Raytheon, in cooperation with Israeli-owned defense contractor Rafael Advanced Defense Systems, builds the Iron Dome system. Here's how Raytheon describes the weapon:

And here's Rafael's take:

Iron Dome consists of three main parts. A sophisticated radar that detects incoming threats. A control system developed by Israeli firm mPrest that takes the information from the radar, instantly analyzes it and computes next steps. And the mobile "firing units," each of which contains 20 Tamir rockets that intercept the incoming fire. Israel employs several of these batteries, which cover roughly 60 square miles (155 square kilometers) each and reportedly cost $10 million apiece.

What makes Iron Dome so effective is its ability to quickly detect what is a real threat (say, a rocket headed toward the heart of a city, a military base or a deployment of troops) and what isn't (say, a flock of birds or a rocket that is on trajectory to cause no harm), and then fire the Tamir interceptor rockets as needed.

According to Raytheon, Iron Dome is designed to detect threats from about 2.5 to 43.5 miles (4 to 70 kilometers) away. It does this, too, as Hamas often fires dozens and dozens of rockets at once ... in addition to mortar, other artillery and even drones.

"Arguably, one of the most impressive elements of this system is its command and control," says Ian Williams, a fellow in the International Security Program at the Washington-based think tank Center for Strategic & International Studies, and the deputy director of CSIS's Missile Defense Project. "These rockets move in very quickly. The engagement timeline, [when] you have to establish control and engage, is very short. It's seconds to minutes. And, also, it's not like these [rockets] come in in ones and twos. They come in in 10s and 20s and 30s or more."

The Tamir rockets, which travel at subsonic speeds (maybe a couple hundred miles per hour), are not guided by human hands. But they are equipped with all sorts of onboard sensors, including things like GPS and electro-optical sensors, and steering fins so that they can automatically adjust their paths en route to track down their prey. Their "fuze blast warheads" explode near the incoming targets (they're not designed to actually hit them, though it happens), destroying them in-air. "The idea is it will detonate the warhead," Williams says. "It doesn't obliterate the rocket completely. It kind of neuters it."

It's not always clean. Fragments from the airborne explosions sometimes cause damage as they return to Earth. But Iron Dome's record is impressive. Rafael claims a success rate of better than 90 percent.

If Hamas or another of Israel's enemies were ever to launch a more potent missile, say a ballistic missile, Iron Dome is not equipped to handle that. Those missiles are bigger and faster, with longer and steeper trajectories. Iron Dome is specifically for shorter-range threats.

As many incoming missiles as Iron Dome can negate, there's some question, too, about its limits. But as long as someone is willing to sell (or give) Israel's enemies ammunition — Iran is a source — the rockets will be a threat and a resolution to the long-simmering conflict seems remote.

Hamas, considered a terrorist organization by many nations (including the United States), may see some long-term advantage in continuing its bombardments, too, despite the Iron Dome. Even though the rockets aren't particularly powerful, and even though maybe only 10 percent get through, that can be dozens, maybe even hundreds of threats Israel has to dodge over an extended conflict.

"The damage is cumulative," Williams says. "It's the volume of them that is the concern, certainly. The destruction of life in general. And just the psychological impact.

"If you read Hamas' and some of the Iranians' remarks and propaganda, they'll talk about the effects of it. They'll say, 'Oh we sent 3 million Israelis scurrying to their bomb shelters.' It's that kind of effect."

Whatever shortcomings it may have, though, the Iron Dome is undoubtedly successful at exactly what it was built to do.