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?