March 19, 2014: The U.S. recently announced it was giving Israel $429 million to buy more Iron Dome anti-rocket batteries and buy more of the Tamir missiles the system uses. The U.S. had already contributed nearly a billion dollars for Iron Dome development and procurement. This latest effort by the U.S. will help Israel put fifteen Iron Dome batteries into service and build up the number of the Tamir missiles. Since 2010 Israel has received eight batteries of Iron Dome anti-rocket missiles. And about two thousand Tamirs.

Israeli developed the Iron Dome system, which has been in service since 2009 and has proven itself in combat. Israel has long wanted fifteen batteries of Iron Dome but that was going to cost more than Israel could afford. Each battery has radar, control equipment, and 3-4 missile launchers (each with 20 missiles) and costs about $37-50 million depending on how many missiles it is shipped with.

Iron Dome uses two radars to quickly calculate the trajectory of the incoming rocket and do nothing if the rocket trajectory indicates it is going to land in an uninhabited area. But if the computers predict a rocket coming down in an inhabited area one (or often two to be sure) $50,000 Tamir guided missiles are fired to intercept the rocket. This makes the system cost-effective. Even so over a thousand Tamir missiles have been used since the system entered service in 2011.

So far Iron Dome has shot down 85 percent of the rockets it calculated were headed for a populated areas. The Tamir missiles used by Iron Dome weigh 90 kg and have a range of 70 kilometers against rockets, mortar shells and artillery shells up to 155mm. Iron Dome can also shoot down aircraft and helicopters (up to 10 kilometers/32,000 feet altitude). Iron Dome is the principal defense against short range rockets fired from Gaza or Lebanon. Work is underway to increase Iron Dome range from 70 to over 200 kilometers. The U.S. supplied much of the money and some of the technology needed to develop Iron Dome and could obtain Iron Dome systems for about as much as the Israeli Air Force pays.

Iron Dome remains a mix of battlefield success and controversy. For example, the Israeli military has had to keep repeating public reminders that Iron Dome was not meant primarily for defending towns and villages but military bases and critical infrastructure (power and water). Each battery can defend about 150 square kilometers and Israel contains 22,000 square kilometers. Only about ten percent of this occupied by residential areas, but you get the idea. This reminder was repeated after Iron Dome successfully defeated a Hamas attack (using 1,500 rockets) against populated areas in late 2012. Many Israelis assumed this meant they could expect similar protection if there were a larger attack from Hamas or Hezbollah. But the military points out that Hamas has over 5,000 rockets and Hezbollah over 40,000. If one or both of these groups fired several thousand rockets, including longer range (over 20 kilometers) ones  the Iron Dome batteries would have to be used to defend military bases and power plants first (otherwise defense of the nation would be imperiled) before trying to cover civilian targets. With a smaller attack the existing number of Iron Dome batteries is sufficient to defend everything, which is what happened last year. But until it is possible to buy more Iron Dome batteries and missiles, a major attack will leave many civilian targets vulnerable. With eight batteries available now there is still a need to concentrate on protecting key targets if there is a major attack. The military believes it would need twenty batteries to cover everything but it is unclear if the government can come up with the money for that. The U.S. is supplying some of the cash for increasing the force to fifteen batteries.

The military has been pointing this out for since 2010. The first mention was in response to announced plans to keep the new Iron Dome batteries in storage once they entered service. At that time politicians were making much of using Iron Dome as a means of defending civilians living close to the border and vulnerable to rockets fired from Gaza in the south and Lebanon in the north. But it turned out that it takes about 15 seconds for Iron Dome to detect, identify, and fire its missiles. Most of the civilian targets frequently under fire from Gaza are so close to the border (within 13 kilometers) that the rockets are fired and land in less than 15 seconds. When longer range rockets are fired there are many more targets (civilian and military) to aim at and Iron Dome is much more effective. This is what happened in late 2012, when Hamas fired many of its longer range rockets at larger towns and cities deeper in Israel.

This explains why, after Iron Dome was declared ready for action in 2011 it was surprisingly (to most Israelis) placed in storage. The air force said they would prefer to save money and put the Iron Dome batteries in storage, to be deployed only for regular tests and training or, of course, for an actual emergency, like an expected large scale attack on southern or northern Israel. Politicians demanded that at least one battery be deployed along the Gaza border. Eventually all the batteries were deployed to defend a constantly shifting array of targets. Moving the Iron Dome batteries a lot is good training and confuses the enemy. Meanwhile the military sees Hamas and Hezbollah stockpiling larger numbers of longer range rockets that would enable massive use of long-range rockets against military bases (most of them more than 20 kilometers from the Gaza or Lebanese borders). The generals believe it's more important to protect the military forces, who ultimately defend Israel, and that's what Iron Dome will now be used for, at least when there is threat of a major rocket attack.

The Palestinians are believed to have tried to defeat Iron Dome by firing a lot of long range missiles simultaneously at a few cities. In theory this could overwhelm one or two Iron Dome batteries. But Israel is able to keep 24/7 UAV watch on Gaza and spot attempts at large scale simultaneous launchers. This enables Israel to bomb many of the launch sites. This results in many rockets destroyed on the ground or launching erratically and landing within Gaza or nowhere near where they were aimed. Because Iron Dome can track hundreds of incoming missiles, quickly plot their trajectory and likely landing spot, and ignore the majority that will not land near people, the Palestinians tried putting hundreds of larger (long range) missiles into the air at the same time to be sure of causing lots of Israeli casualties. So far the Palestinians have not been unable to get enough rockets into the air at the same time to make this work. They may never get this to work, because they have to hide preparations for the simultaneous launch of many rockets and this is very difficult to do undetected.

The Palestinian rocket attacks have been around since 2001, but got much worse once Israel pulled out of Gaza in August of 2005. This was a peace gesture that backfired. From 2001 to 2005, about 700 rockets were fired from Gaza into Israel. Since the 2005 Israeli withdrawal, over 5,000 more rockets were fired into Israel. The rate of firings increased after Hamas took control of Gaza in June, 2007. In 2011 700 rockets and mortar shells were fired, this jumped to 2,300 in 2012 when Hezbollah briefly went to war with Israel. The retaliation was so effective that Hezbollah agreed to a ceasefire. Thus since the early 2013 ceasefire only a few hundred 40 rockets and mortar shells have landed in Israel.