RENEE MONTAGNE, HOST:
It's MORNING EDITION from NPR News. I'm Renee Montagne.
STEVE INSKEEP, HOST:
And I'm Steve Inskeep. Israel and Hamas are exchanging airstrikes and rockets. And in this part of the program, we'll hear what it is like to be underneath them.
MONTAGNE: We begin with a striking number - zero. That's the number of Israelis known to have been killed by Hamas rockets so far. Israel's military credits a rocket defense system known as the Iron Dome. NPR's Ari Shapiro reports.
ARI SHAPIRO, BYLINE: Two or three decades ago, lots of people in Israel's military thought missile defense was a bad idea.
UZI RUBIN: I'd say that the traditional military analyst didn't see the reason why deal with defense at all.
SHAPIRO: Uzi Rubin remembers that time well. Back then, he ran Israel's missile defense program. Now retired, he says the old bulls used to tell him the only defense Israel needed was a good offense.
RUBIN: And it wasn't easy to get the budgets and the support at that time. Actually, it was against the wind really.
SHAPIRO: But eventually the budgets came, helped along by the U.S., which gives Israel hundreds of millions of dollars a year for rocket defense. And now virtually every Israeli newscast includes a tally of the number of rockets fired from Gaza and the number intercepted by Iron Dome.
SHAPIRO: We've driven through fields of watermelon and potatoes. We're now on the outskirts of the city of Ashkelon, not far from Gaza. We can see the city buildings on the horizon. And in the middle of this field, at the end of dirt road, there's a military barricade. And behind the barricade, two huge vehicles the size of flatbed trucks with what looks like great, big spotlights pointed at the sky. But these are not spotlights.
PETER LERNER: The Iron Dome has two main outside vantages.
SHAPIRO: That's Israeli military spokesman Peter Lerner came out to this field to tell us about the technology.
LERNER: First, obviously, it saves lives. It intercepts that rocket, which if it wouldn't have been intercepted would strike the heart of the population. The second advantage it gives us - it gives us as a leadership the capability to step back and make coolheaded decisions.
SHAPIRO: Israel's onslaught of Gaza is plenty aggressive - hundreds of airstrikes, civilian deaths and hospitals overflowing with injured Palestinians. But Peter Lerner says if Israelis were being killed in large numbers, people would push for an even more aggressive response - a ground invasion. He says Iron Dome lets the Israeli government breathe.
LERNER: You can make the decision when you feel free to do so, and at your advantage, not because they've drawn you in to this cause-and-effect scenario.
SHAPIRO: We just heard a couple of low booms. And in the sky there are two trails of smoke. And at the end of the trail in the middle of the sky, two white little puffs, almost like tiny clouds.
MICHAEL OREN: So it works.
SHAPIRO: Michael Oren was Israeli ambassador to the U.S. He says these interceptor rockets cost millions of dollars each, so they only fire when the incoming weapon is on a trajectory to hit a populated area.
OREN: One of the ingenious qualities of the Iron Dome is that within a fraction of a second can distinguish between a trajectory that's going to bring a rocket into downtown Be'er Sheva or Ashkelon and a rocket that's going to hit an empty field or fall in the ocean.
SHAPIRO: Iron Dome's critics claim that Israel's military's vastly overstates the technology's effectiveness and that it might only hit its target 5 percent of the time. So I asked former defense official Uzi Rubin if there's any independent way to measure how well it works.
RUBIN: Yes. You can judge it by public information about casualties and damages.
SHAPIRO: Iron Dome was first used in the 2012 conflict. And Rubin says if you compare the number of deaths and damage claims in that conflict to previous ones, there's a dramatic drop. Israel sees this Iron Dome as just the first of several steps. Next up is a technology known as David's Sling. Its goal would be to intercept more advanced and longer-range rockets and cruise missiles. Ari Shapiro, NPR News, Jerusalem. Transcript provided by NPR, Copyright NPR.