Updated

In four days of fighting against Gaza-based militants, Israel has used a missile-defense system called "Iron Dome" to intercept rockets fired at populated civilian areas. It says the new home-grown system has been a tremendous success.

As of Saturday evening, the military said it had shot down some 240 incoming rockets, more than half the number of projectiles launched into Israel since Wednesday.

Here's a quick look at the system:

— Produced by Israeli-based Rafael Advanced Defense Systems, Iron Dome is meant to shoot down rockets and artillery shells with ranges of up to 70 kilometers, or 45 miles. It has been operational since 2011.

— How it works: The system detects launches of rockets and quickly determines their flight path. If it is headed toward populated areas or sensitive targets, it fires an interceptor with a special warhead that strikes the incoming rocket within seconds. Rockets headed toward open areas area allowed to land.

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— Currently, five Iron Dome batteries are deployed in Israel. Most are located in the south near Gaza. A fifth battery was deployed outside Tel Aviv on Saturday, two months ahead of schedule. Hours later, it shot down a rocket headed toward Tel Aviv.

— Missiles cost around $40,000 a piece. In 2010, the U.S. provided $200 million to expand development. Additional funding is currently being considered, with $70 million already allocated for the 2012 fiscal year.

— The system is part of what Israel calls its "multilayer missile defense." It is meant to protect against the tens of thousands of short-range rockets possessed by militants in the Gaza Strip and Hezbollah guerrillas in Lebanon. Israel has also deployed its "Arrow" missile defense systems for long-range threats from Iran.

The military says its new "David's Sling" system, being developed by Rafael to stop medium-range missiles, will be activated by 2014.