June 5, 2019: While the Israeli Iron Dome anti-rocket system has been successful since it entered service in 2011, a May 2019 attack with 700 rockets and mortar shells fired from Gaza demonstrated a known weakness. Although Iron Dome has handled 2,100 interceptions since 2011 the recent May attack was the first time the Islamic terrorists deliberately tried to exploit the one known weakness; you can overwhelm an Iron Dome battery if you fire too many projectiles in a short period of time. The 2019 attack killed four Israelis and wounded 130. The concentrated rocket fire meant 14 percent of rockets headed for populated areas were not stopped. Worse, the Palestinians were using larger rockets fired at more distant (and densely populated) targets. In previous attacks, Iron Dome had intercepted 90 percent of rockets headed for populated areas.

Iron Dome faces two major threats. In Gaza, Hamas and Iran backed Islamic Jihad each have over 10,000 rockets available. In the north, Iran-backed Hezbollah has over 30,000 rockets in southern Lebanon. Both of these groups could jointly unleash a massive launch of rockets. They are dissuaded by most Lebanese, who do not support Hezbollah and see that organization as a growing threat to Lebanon rather than a defender. Israel has told Lebanon that if Hezbollah attacks the Israeli retaliation will be against all of Lebanon and the damage to infrastructure will be massive. In the south, Israel and Egypt have both warned of dire consequences if a massive rocket attack is launched on Israel. Most Gaza residents also oppose another war with Israel. Dire threats don’t always work with Islamic terror groups but Israel has a long record of actually delivering on the retaliation. So it is difficult to hope massive damage can somehow be avoided. Moreover the more you threaten Israel, the more money and effort they spend on preparing for attacks. For example, money for Iron Dome upgrades (longer range rockets linked batteries fire control) and more batteries have been stalled by defense budget restrictions. That tends to change if the mass rocket threat is seen as increasing.

Using Iron Dome effectively has always been a matter of numbers. In the 2014 50-day war with Hamas, Iron Dome intercepted 735 Hamas rockets, which were 90 percent of those headed for populated or military base areas. That was up from the eight-day 2012 war where there were 421 intercepts and of those 84 percent were headed for populated or military base areas. The 50-day war faced 9,000 Hamas rockets, of which 40 percent were locally made. The local models are less accurate and reliable than the factory made rockets. More of the locally produced rockets never made it into Israel, either exploding in the air or falling within Gaza. The factory made rockets were much more reliable.

Hezbollah has nothing but Iranian factory made rockets. How many Hezbollah could launch (as many as ten times what Hamas got into the air during the 2014 war) depends on what disruption plans (air, ground and special operations) Israel has and how effective these plans are. This has Hezbollah worried because they noted that Hamas underestimated Israel during the 2014 war and saw all their “secret weapons and special plans” fail. The Israelis are determined to do the same to Hezbollah. On top of this Hezbollah has suffered heavy losses in Syria, where they were ordered by their Iranian backers to join the effort to keep the Assad government in power. Iran has long supported both Hezbollah, the Assads and Islamic Jihad in Gaza. The problem is that most Lebanese hate the Assads and Syrians in general. Thus Hezbollah efforts to support the Assads have been very unpopular in Lebanon and this has made it easier for Israel to gather intelligence on the ground and support from some anti-Hezbollah Lebanese factions. Recently the increased impact of restored (in early 2017) American sanctions on Iran were felt by Hezbollah. In 2019 Iran began sending half as much cash has they had been supplying. This led to pay cuts or unemployment for thousands of Hezbollah employees.

For a long time, the Hezbollah threat was greater not just because they have more rockets, but because a growing percentage of them (over 5,000) are long range models that can reach just about everywhere in Israel. More of these are being equipped with GPS guidance, meaning a higher proportion of rockets will be certain to hit populated areas unless intercepted. These, as Hezbollah likes to point out, could shut down all the ports and airports in Israel, at least to commercial traffic. Israel has been working on deploying its ten Iron Dome batteries in the north and use them to concentrate on the longer-range rockets. But Iron Dome is seen as the last defense line. The primary weapon against all those rockets is intelligence, diplomacy (with local opposition factions in Gaza and Lebanon) and precision weapons (bombs, missiles and shells). Another powerful weapon are threats Israel had demonstrated, many times in the past, they are willing to carry out. One of these is to tell the residents of southern Lebanon, near the Israeli border, that if there is even the credible threat of a mass Hezbollah attack, Israel will hit known Hezbollah rocket stockpiles with rockets and airstrikes. This is scary because Hezbollah has built homes, hospitals, Mosques and schools over these stockpiles. The civilians living over these rocket storage sites know they are human shields but live there anyway because the houses were cheap and the risk of Israel attacking residential areas was remote. Israel can declare the threat no longer remote but a certainty. The Israelis would do this if they calculated a mass Hezbollah attack would result in heavy Israeli civilian casualties. Most Israeli Arabs live in the north and they have also been demanding better defenses against Hezbollah.

Meanwhile, Israel has developed planning and predictive analytics software to help with outsmarting Hamas. This is nothing new as the key to Iron Dome’s success is its software. Iron Dome uses two radars to quickly calculate the trajectory of the incoming rocket and does nothing if the rocket trajectory indicates it is going to land in an uninhabited area. This means the software can also tell if the rocket is going deep into Israel. If the software predicts a rocket coming down in an inhabited area, a Tamir guided missile is fired to intercept the rocket. This software has been very successful.

In the north, against Hezbollah Iron Dome will also be able to prioritize Tamir launches to go after the rockets predicted to do the most damage. This makes the system very efficient and cost-effective. That's because most of these unguided rockets land in uninhabited or thinly populated areas but the few of those that do land in populated areas inflict casualties. Those long-range rockets can land in very densely populated urban areas.

There’s nothing special about most of the Iron Dome components. The Tamir missiles each weigh 90 kg (200 pounds), are three meters (9.8 feet) long, and 160mm in diameter. They have the usual components of a guided missile (rocket motor, electronics, and mechanical devices to actuate the fins and batteries). Such interceptor missiles are increasingly common, but usually against much faster ballistic missiles. Without the predictive software, Iron Dome would quickly run out of missiles and be much more expensive to operate as well.

Israel had bought ten Iron Dome batteries and has so far been unsuccessful in obtaining the cash to purchase another five. Each of the Iron Dome batteries has radar and control equipment and three or four missile launchers (each containing twenty missiles). Each battery costs about $50 million, which includes up to a hundred Tamir missiles. These cost $40,000 each. That’s down from $90,000 each because of design improvements and production in larger quantities.

In addition to buying more batteries, the manufacturer is also offering an upgraded Tamir design that has a range of 250 kilometers (versus the current 70 kilometers). This would enable batteries to overlap coverage and concentrate fire against mass rocket launches during a short period of time. Then there is the larger proportion of rockets being larger (more explosives in the warhead) and guided (more will head for populated areas). This may prompt buying five more batteries and the longer range Tamir missile. The only alternative is to use the new David’s Sling anti-aircraft missiles against the larger guided rockets. The problem is that David’s Sling interceptor missiles cost a million dollars each and there are far fewer of them in inventory.