A counter-missile is launched by the Iron Dome system.

A counter-missile is launched by the Iron Dome system. Photo: AFP

Ashkelon: In a sun-scorched field on the outskirts of the Israeli city of Ashkelon, out of sight of the locals busy picking ripe watermelons nearby, two state-of-the-art anti-missile defence batteries stand on high alert.

Shaped like two giant matchboxes tilted diagonally towards Gaza, the system comes to life as the wailing of a siren echoes through the nearby loudspeakers.

Explosion of rockets from Gaza and the the Iron Dome above Sderot, Israel.

Explosion of rockets from Gaza and the the Iron Dome above Sderot, Israel. Photo: Getty Images

In the time that it took to read the two sentences above, the Iron Dome system will have determined whether the rocket soaring through the sky is likely to land in an open field or crash into a building in a city. In case of the latter, a counter-missile will already have been deployed to intercept it. Such a process has been repeated many times since Monday.

More than 360 rockets have been launched at Israel from Gaza in this time. Of these, the Iron Dome has intercepted more than 70, including approximately 10 missiles that were fired at Tel Aviv.

The number of interceptions may seem low, but the system, designed and built by Rafael Advanced Defence Systems in 2011, is configured to only destroy the rockets poised to hit urban or strategically sensitive areas.

Each interception missile fired is priced at $US50,000 ($53,000). In the war with Gaza in November 2012, the Iron Dome blocked almost 500 rockets - a total cost of $US25 million.

There are seven Iron Dome batteries deployed around the country, and so far they have had an almost 90 per cent interception success rate. Challenges for the system are always changing, with an increased numbers of rockets coming from Gaza with increased destructive range.

The Iron Dome is also susceptible to occasional failures. In the 2012 war, an error resulted in a rocket crashing through the walls of a house in Kiryat Malachi, southern Israel, killing three people and critically injuring a child. Rafael said the system has since undergone significant upgrades and improvements.

Telegraph, London