August 24, 2011: Terrorist groups in Gaza have figured out how to get around the new Israeli Iron Dome anti-rocket system. All you have to do is fire at least seven rockets simultaneously at the same area being guarded by one Iron Dome battery. Islamic terrorists did this recently. One rocket got through, and killed an Israeli civilian. This “saturation” tactic is a problem with all air defense systems.

Israel has bought seven batteries of Iron Dome, to be delivered over the next two years. Two are in service, and a third will be ready by the end of the year. Each battery has radar and control equipment, and four missile launchers. Each battery costs about $37 million, which includes over fifty missiles.

During tests, Iron Dome detected and shot down BM-21 (122mm) and Kassam (crude versions made inside Gaza) rockets. Iron Dome uses two radars to quickly calculate the trajectory of the incoming rocket and do nothing if the rocket trajectory indicates it is going to land in an uninhabited area. But if the computers predict a rocket coming down in an inhabited area, a $40,000 guided missile is fired to intercept the rocket.

This makes the system cost-effective. That's because Hezbollah fired 4,000 rockets in 2006, and Palestinian terrorists in Gaza have fired over six thousand Kassam rockets in the past eight years, and the Israelis know where each of them landed. Over 90 percent of these rockets landed in uninhabited areas, and the few of that did hit inhabited areas caused few casualties. Still, a thousand interceptor missiles used against another major attack would cost $40 million. But that would save large quantities of military equipment and avoid many dead and injured troops and civilian. Israel already has a radar system in place that gives some warning of approaching rockets. Iron Dome currently uses that system, in addition to another, more specialized radar in southern Israel.

Firing salvos of rockets at once is more difficult, and dangerous, than firing one or two at a time. The larger number of rockets takes longer to set up, and makes it easier for the Israelis to spot the preparations and fire a Hellfire missile. Moreover, the Iron Dome system control software can be tweaked to handle more simultaneous targets, and the fire control hardware can be upgraded as well. So the new terrorist tactic won’t remain successful for long.