When Israel launches air strikes and artillery bombardments on Gaza, Palestinians have few sources of protection. But when Palestinians fire rockets into the Jewish state, its citizens can bank on one of the world’s most tried and tested air-defence systems for security — the Iron Dome.

Hamas, the Palestinian militant group that controls the Gaza Strip, has since Monday launched more than 2,000 rockets on Israel, targeting major cities such as Jerusalem and Tel Aviv as well as other towns.

The Islamist movement has maintained its barrage even as Israeli fighter jets, artillery and tanks have pounded the impoverished Palestinian territory of 2m people. At least 122 people have been killed since Monday in Gaza, including 31 children and 20 women, and 900 others wounded, Palestinian medical officials said.

But, according to the Israeli military, close to 1,000 of the Palestinian rockets have been intercepted by the Iron Dome, a system built by Israeli defence companies and funded and developed jointly with the US. The Palestinian rockets have killed nine Israelis, including a child, while a woman died as she ran to a shelter and a soldier was killed by an anti-tank missile.

“The number of Israelis killed and wounded would be far higher if it had not been for the Iron Dome system which has been a life saver as it always is,” said Lt Col Jonathan Conricus, the Israeli military’s spokesman.

Diagram showing the working of Israel

The Iron Dome was designed specifically to deal with the more rudimentary and shorter-range missiles fired at Israel by Palestinian factions, and was first used 10 years ago to intercept projectiles fired by Hamas from Gaza. Its development was accelerated after Israel’s month-long war in 2006 with Hizbollah, the Lebanese movement backed by Iran, and its conflict with Hamas three years later.

Justin Bronk, a research fellow at the Royal United Services for Defence and Security Studies, said a large part of Iron Dome’s success was due to a sophisticated radar system that enables it to determine rapidly which incoming rockets are likely to strike built-up areas and which will land harmlessly on open ground. The Israeli military says it is 90 per cent effective.

Iron Dome has 10 batteries deployed around the country, each with three to four launchers that can fire 20 interceptors, giving the system the ability to launch up to 800 missiles at incoming rockets, without counting reloads.

As it is designed to counter shorter-range, slower-moving rockets, the missiles it uses are relatively small and cheap compared to those used in other air defences, such as the US Patriot system, with the interceptors costing between $40,000 and $100,000, Bronk said.

The Obama administration stepped up US funding for Iron Dome partly to show support for Israel. But it also hoped it would help prevent conflicts from escalating.

“It was a deliberate calculation by the Obama administration to fund it with [general] American rather than just US military aid to the tune of, eventually, about $1.5bn,” Bronk said. He added that one condition was that the Americans could use the interception data for their own research and development purposes.

Ulrike Franke, a senior policy fellow at the European Council on Foreign Relations, said this week’s events underlined the “political importance” of Iron Dome which made it possible for Israelis to “continue a somewhat normal life while under attack”.

“It gives the government leeway — if Hamas attacks killed hundreds of Israeli civilians, the Israeli government would be pushed very hard to intervene with a ground operation,” she said. “With the protection of Iron Dome, the government has more freedom of manoeuvre. However, on the other hand, it also gives the government freedom to not try and find a peaceful solution — as it can endure, at least for a while, the attacks.”

But the scale of the salvos fired this week by Hamas has still shocked Israelis, striking terror into neighbourhoods where rockets have breached the defences.

“I know I am not supposed to be scared, but you hear the sirens, and you panic — what if you are the unluckiest man in the country today?” said Tomer, shuffling into a garage in Jaffa with his infant child. Minutes later, an Iron Dome interceptor took out a rocket overhead, leaving smoke trails in the sky.

The Israeli army was also surprised Hamas was willing to launch such a campaign against the Middle East’s best-equipped and most sophisticated military force and risk the consequences.

There is the risk that a sustained barrage of hundreds of rockets could overwhelm the system. Hizbollah possesses a bigger and far more sophisticated stockpile of rockets than Palestinian militants.

“Hizbollah has an arsenal of more than 100,000 rockets and is much better equipped to fire sustained volleys in large numbers,” Bronk said. “A lot of its rockets are also now being equipped with Iranian guidance devices so they are more accurate, which also increases the number of those Iron Dome would need to intercept.”

But he added that Iron Dome was never intended to be “a total defence”.

“In many ways it changes the game psychologically more than it changes the overall balance of forces in any large-scale clash,” Bronk said.

Additional reporting by Mehul Srivastava in Tel Aviv