Center for Strategic Communication

An Iron Dome battery near Sderot, Israel. Photo: NatanFlayer/Wikimedia

The top U.S. military officer’s plane got damaged in Afghanistan by insurgent rockets on Tuesday morning. It’s a reminder that the U.S. military’s defense against short-range rockets remains a work in progress. But it has helped its ally Israel buy its own system for defending against exactly those kinds of rockets, and it might be useful for the U.S. to ask Israel to share. Only one problem: The U.S. doesn’t quite know how the Iron Dome system works.

That’s a bit of an oversimplification. The broad outlines of the Iron Dome system are widely understood: It’s a mobile set of interceptor batteries capable of shooting down rockets that adversaries launch from a distance of between five and 40 kilometers — difficult targets to hit, since they fly low, in a straight line, and quickly. (At most, rockets like the Grad or the Kassem, used by Israel’s jihadist enemies, take 40 seconds to hit their targets.) Using radar and a bit of math, the Iron Dome software figures out if a rocket is likely to land near a populated area. If so, Iron Dome fires its interceptor; if not, it finds a rocket that might.

With Hamas firing short-range rockets into southern Israel and Hezbollah stockpiling more on Israel’s northern border, it’s no wonder Israel is singing the praises of Iron Dome. (Well, that and the fact that it’s the rare weapons system that sounds like it came from the Wu-Tang Clan’s arsenal.) The Israelis say it has an an 80 percent success rate — which is all the more impressive when considering that the rockets Iron Dome shwacks can take as little as five seconds to hit a target.

Israel didn’t buy Iron Dome on its own. America chipped in $200 million, and if a proposal in next year’s defense bill becomes law, that number will increase to around $900 million. (Each Iron Dome installation costs about $50 million, plus another $62,000 per interceptor.) Sounds like something the U.S. might want for itself, perhaps?

But there’s a problem. In the Pentagon and on Capitol Hill, there’s widespread confusion about the details of Iron Dome’s operations. See, Israel might have had help buying Iron Dome, but it developed Iron Dome all by its lonesome. On Iron Dome’s specifics, the U.S. is largely in the dark. Congress wants to fix that.

As mentioned by Politico on Monday, the House Armed Services Committee recently asked the Missile Defense Agency to explore “any opportunity to enter into co-production of the Iron Dome system with Israel, in light of the significant U.S. investment in this system.” According to committee spokesman Claude Chafin, the problem is that the U.S. doesn’t have the necessary transparency into the details of Iron Dome that it has with other U.S.-Israeli anti-missile partnerships, like Arrow and David’s Sling — an opacity that makes it hard to argue the U.S. should get its own Iron Domes for ships and bases. So the committee wants to condition the next round of $680 million in Iron Dome funding on that knowledge.

That’s not exactly a Pentagon priority. In May, when the Pentagon announced it would give Israel more cash for Iron Dome, Danger Room asked if it was exploring domestic uses for the system. Defense Department spokesman George Little said “the focus of Iron Dome is, of course, on Israel at this stage.”

Meanwhile, U.S. bases in Afghanistan and Iraq experienced nearly a decade of attacks from rockets and mortars. The defensive systems used on those bases are typically a Phalanx Gatling gun, adapted from Navy ships. The gun fires a 20-millimeter round at an incoming mortar after triangulating its trajectory through radar. Hopefully the bullets hit. If they don’t, the rounds are programmed to self-destruct (.pdf). They are also — and this is your word of the day — frangible, which means they degrade into a gazillion tiny pieces, minimizing the risk of harming a civilian.

But the Phalanx doesn’t work well with low-flying rockets. And even with the frangible rounds, concerns with hitting innocents abound. That’s why when a base is attacked, sometimes the only real countermeasure taken is to warn troops to duck and cover. (A spokesman for the NATO command in Afghanistan wouldn’t say what countermeasures it took when Dempsey’s plane was attacked.)

Even if the military isn’t really able to use Iron Dome at present, the interest in creating something like it is clear. Last week, the Army asked its industry partners if they could come up with something that could intercept rockets, mortars and missiles with ranges of 2.5 kilometers — which is beyond what the Israeli version can destroy — and would also take down drones. “Concepts should have sufficient stowed kill capacity (80 to 300 engagements per platoon) and be to support a large number of simultaneous incoming threats (60 engagements in 20 seconds) arriving from the same or different azimuths,” reads an Army request for information. A response time of “about 13 seconds” is necessary.

Alternatively, there’s the laser option. Admittedly, lasers have been held out as a panacea for incoming missiles for years, and they’ve yet to pan out. But in the fall, the Army’s Space and Missile Command anticipates testing a solid state laser capable of shooting down rockets, mortars, missiles and drones, InsideDefense reports. A 10-kilowatt beam ought to be sufficient for the test this fall, the Army thinks, although it’ll want to scale up to 50 kilowatts if any system resulting from the test reaches maturity. (100 kilowatts has traditionally been considered the starting point for military-grade lasers, however.)

Maybe the lasers pan out, maybe they don’t. But there’s a simpler way the U.S. might start developing better defenses for incoming rockets: arrange with Israel to let the U.S. military get a closer look at Iron Dome; and figure out if it’s worth getting a Dome of its own.