How does Israel's defense system against Iranian missiles work, and what is its cost?

Following Iran's missile attack on Israel on October 1st, numerous fake or miscontextual videos appeared on social media platform X, depicting missile strikes on Israel.

Some users quickly asserted that Israel's lauded Iron Dome defense system had failed. Others speculated that Israel may have deliberately allowed the Iranian missiles to land on its territory to set a precedent for retaliatory strikes against Iran.

However, such statements are false.

Even if a missile strikes an empty area in Israel, that doesn't necessarily indicate a failure of the Iron Dome system or that the missile was intentionally landed as part of a strategy to retaliate against Iran.

And in this particular case, it appears that Israel may not have relied on the Iron Dome defense system.

Which missiles did Iran use?

Reports indicate that Iran fired approximately 180 ballistic missiles into Israeli territory.

Ballistic missiles operate on the principle of providing initial energy from a powerful propulsion engine to propel the missile to very high altitudes and speeds. After the engine stops, the missile enters a free-flying phase along a parabolic trajectory, similar to a bullet fired upwards. This trajectory is called a ballistic trajectory.

During the free flight phase, the missile no longer has a propulsion system but is only subject to gravity and air resistance (if still moving in the atmosphere). Therefore, the missile cannot adjust its flight path during this phase. The range and accuracy of a ballistic missile depend on many factors, including the launch angle, initial velocity, type of warhead, and meteorological conditions.

Israel claims that, with the help of the US and UK, they shot down most of the Iranian missiles, although some damage may have occurred on the Israeli side. A BBC journalist in Lebanon said the missiles may have struck Israeli military bases as well as a restaurant and a school.

Meanwhile, Iran's Islamic Revolutionary Guard Corps claimed that 90 percent of its missiles hit their targets, including three military bases.

It remains unclear what type of missile Iran used, although based on the videos, experts told CNN that Iran may have fired a Shahab-3. This is a medium-range missile capable of flying approximately 500-600 miles.

Some reports in Iranian media suggest that Iran may also have deployed Fattah-1 hypersonic missiles.

How does Israel's defense system work?

Israel's most well-known air defense system is the Iron Dome, manufactured by domestic companies such as Rafael Advanced Defense Systems and Israel Aerospace Industries. On its website, Rafael Advanced Defense Systems claims that the Iron Dome defense system has intercepted more than 5,000 missiles with a success rate of over 90%.

The Iron Dome defense system has helped repel numerous Hamas attacks over the years. However, this time Israel appears to have relied on other defense mechanisms, as the Iron Dome is only used for short-range missiles with a range of up to 43 miles.

One of these is David's Sling, which has a range of 25 to 190 miles and is designed to intercept medium-range threats.

For longer-range missiles, Israel uses the Arrow 2 and Arrow 3, which operate outside the atmosphere. For example, the Arrow 3 is said to have a range of over 1,500 miles.

All of these systems include missile defense systems equipped with missile launchers and radar capable of detecting missiles and other threats, such as drones, aircraft, and other projectiles.

After detecting the missile, artificial intelligence (AI)-assisted algorithms will help determine its trajectory, and interceptor missiles will be fired from the launcher to destroy it.

The Iron Dome defense system can also allow short-range threats to strike the ground if it determines the missile is heading toward an uninhabited area, thus saving on the cost of interceptor missiles.

How much does it cost Israel to shoot down a missile?

While estimates suggest that manufacturing a missile for Iran could cost around $100,000 or more, the cost for Israel to neutralize these threats is believed to be significantly higher.

Reem Aminoach, a former Brigadier General and financial advisor to the head of the Israeli military, previously told Bloomberg that repelling the earlier Iranian attack in April may have cost Israel around $1.1 billion. At that time, Iran fired more than 120 missiles, including 30 cruise missiles, and deployed approximately 170 drones.

A significant portion of the cost of repelling such an attack is spent on interceptor missiles. The cost of a David Sling missile is estimated at around $1 million, while some suggest firing an Arrow missile could cost around $2 million.

According to The Guardian, a former financial advisor to the Chief of Staff of the Israel Defense Forces (IDF) said that an Arrow missile typically costs $3.5 million.

Considering Israel's reliance on Arrow missiles, the cost of interceptor missiles alone could amount to at least several hundred million dollars.