Israel's Iron Dome counter-rocket system has been a critical factor in blocking a massive missile onslaught from the Hamas-ruled Gaza Strip.

Many Israelis see it as a "wonder weapon." But as an official at state-owned Rafael Advanced Defense Systems, which produces Iron Dome, observed, that could be a problem "because there aren't enough of these things.

"People see Iron Dome as a savior. We've warned that the danger is that people feel so secure with Iron Dome they don't take security precautions when they hear sirens. They film the rockets on their mobile phones."

Since fighting began last Wednesday, Palestinian extremists have fired more than 1,000 rockets. Iron Dome has shot down around 300. That's around 80 percent of those it engaged; the system only responds to missiles heading for populated areas or vital targets.

There are no comparisons because Iron Dome is one of a kind, developed at a cost of $1 billion. Much of the funding came from the United States.

Four days ago, the most sophisticated version of the weapon built by Haifa's Rafael was thrust into combat two months ahead of schedule to protect Tel Aviv, Israel's largest city, from Iranian-built Fajr-5 missiles and swiftly proved its rocket-wrecking power.

That's a major success for Rafael and other Israeli defense companies, such as Elta, which developed the detection and tracking radar, and mPrest, the battle management interception guidance unit.

For the Israelis, the Hamas rocket attacks on Tel Aviv and apparent attempts to hit Israeli targets in the holy city of Jerusalem, which Israel calls its "eternal capital," are a rehearsal of sorts for the feared onslaught of Iranian, and possibly even Syrian, ballistic missiles if a full-scale war breaks out in the region.

Israeli officials say that could involve up to 200 missiles a day falling on Israeli cities for up to two months, an unprecedented barrage that for the first time in the 64-year-old Arab-Israeli conflict will concentrate on the civilian population.

Iron Dome was developed after the 2006 war with Lebanon's Hezbollah which unleashed 4,800 missiles and rockets on northern Israel in the 34-day conflict. Israel had no defenses for that.

In March 2011, Iron Dome was deployed outside the Negev Desert city of Beersheba to counter Hamas' short-range Grad and Qassam rockets and swiftly got its baptism of fire. It knocked out around 75 percent of those projectiles it engaged, a major success.

A more advanced version was thrown into action Saturday, two months ahead of its planned deployment. It made its first interception soon after and has racked up a 90 percent kill rate. It's positioned at Gush Dan south of Tel Aviv in central Israel, specifically to protect the country's commercial capital.

Four regular Iron Dome batteries are deployed outside Beersheba, Nevitot in the Negev, and the southern coastal cities of Ashdod and Ashkelon, which have long been within range of Hamas' rockets.

The military says it needs at least 13 batteries to effectively cover the nation, Defense Minister Ehud Barak is seeking $190 million to produce three more and expand the Iron Dome program.

The system's command computer is designed to engage only those rockets or missiles whose plotted trajectory indicates they will impact in populated areas or critical infrastructure.

Incoming missiles deemed headed for open ground are disregarded.

Each truck-towed Iron Dome battery is armed with three launch units, each containing 20 Tamir radar-guided interceptor missiles with proximity-fused warheads.

An interceptor costs around $40,000, so the number of Tamirs expended so far in Operation Pillar of Defense have cost Israel around $16 million. That's an expensive proposition when used against Qassam rockets that cost $200 to manufacture in Hamas' clandestine workshops in Gaza's teeming refugee camps.

But, military planners say, that's a lot cheaper than getting caught up in a full-scale war that costs around $380 million a day.

Rafael, which is also developing another system called David's Sling to counter missiles with a range up to 180 miles, says Iron Dome can provide cover for a large city of some 40 square miles against rockets with ranges of 3-45 miles.

The company says Iron Dome's computer system even calculates the safest spot to blow up an incoming missile.