On Sunday, the security cabinet authorized NIS 811 million for "Iron Dome," a defense system against short-range rockets, such as those that have been terrorizing Sderot for the past seven years. If produced according to schedule, the system should be able to start shooting down missiles in about 30 months. The only shame about this decision is that it was not taken years ago. According to Uzi Rubin, the former head of Israel's Arrow missile defense program, the system that Raphael hopes to deliver in 2010 could have been deployed in 2003 if a decision to fund the program had been made in 2000. The obstacles were not technological but judgmental, based on the notion that such defenses are "too expensive." Shooting down missiles can indeed be an expensive enterprise. The planned Raphael system is kinetic, meaning it will shoot a projectile at a rocket. This was deemed more cost effective than competing laser-based systems, even though each firing of a laser is much cheaper than each firing of a kinetic system. The reason is that kinetic launchers are much cheaper than the devices that fire high-powered lasers, which also means more of them can be deployed over a given area, making them harder to overwhelm with a barrage of missiles. It is estimated that even the "cheap" Raphael system will cost about $30,000-$40,000 to shoot down a single Kassam missile. This sounds expensive, given that a Kassam costs a small fraction of that to produce and shoot. The argument against defenses, particularly for use to thwart cheap, short-range missiles, is that the enemy can afford to shoot many more than Israel can shoot down. Rubin suggests, however, that this is the wrong way to calculate cost effectiveness. What matters is that the alternatives are either much more expensive or unacceptable: "hardening" entire cities, a massive ground incursion into Gaza, evacuating Sderot and other towns, or allowing the status quo to continue. The first two options cost much more than Iron Dome and have serious drawbacks. A city cannot be "hardened" against missiles completely, and a ground operation would cause many IDF casualties. Evacuating cities is unacceptable, as is the status quo, which, in any case, is liable to worsen if Israel does not address the missile threat. The Iron Dome system would be able to shoot down both the Kassams that have plagued the South and the Katyushas and Scuds used against the North during the Second Lebanon War. Further, this system would join the Patriot, Arrow and eventually the Arrow 2 missile defense systems, which together would protect the country against a range of short- and long-range threats. According to Defense Minister Ehud Barak, Israel could have an integrated system capable of shooting down 90 percent of short- and long-range rocket attacks. This brings us to the other major argument against missile defense; that a 90% effectiveness is almost worthless, since the 10% that gets through can cause so much damage, particularly in the case of long-range missiles with nonconventional warheads. We disagree. Certainly in the case of smaller missiles, reducing the threat by 90% or more would be a substantial improvement. Similar arguments were made against the security fence for years, since it would not stop missiles, and still is not complete. But we have seen that even the partially completed security fence, when combined with offensive operations, has substantially reduced terrorism and saved many lives. The same is true regarding more serious threats. Defenses are no panacea, but they can be a critical part of a comprehensive strategy that includes deterrence, diplomacy and offensive operations. The alternative to defenses is putting all the security burden on the other elements, all of which can fail or have serious drawbacks when employed on their own. It simply makes no sense for a country, particularly one in Israel's situation, to leave its population literally defenseless against missile attack. Missile defenses - combined with other measures - are critical to making Kassams, Scuds and Katyushas obsolete, just as the security fence was to defeating suicide bombers. The dichotomy between military measures and the peace process is a false one. The goal is peace, but removing military options from our enemies is critical to getting there. The less vulnerable Israel is, the greater the potential that diplomacy can lead to a sustainable peace.