Iron Dome is claimed to have been successful, having shot down perhaps 80% (cumulative) or 90% (in recent conflict) rockets aimed at inhabited areas. But it is also dangerous, since policy makers might take the wrong “lessons learned”. And in fact, they appear to be doing just that.

But the Iron Dome is a completely invalid comparison to make with intercontinental nuclear missiles. First, it was not completely successful: it failed to shoot down seven rockets at least. Seven ICBMs are a far greater problem than seven rockets. Single DF-41 may carry up to 12 warheads with up to 150 kt yield. LGM-30G (Minuteman III) may carry three W-62 warheads with up to 170 kt yield. UR-100N has 6 400 kt warheads. R-36 has 10 warheads up to 750 kt yield, as well as 40 decoys. RS-24 may carry 4-6 150 kt warheads or 3-4 300-500 kt warheads, while RT-2 has a single 1 Mt warhead. Russia has 50 UR-100N, 40 R-36, 140 RS-24 and 78 RT-2. This means, in the worst case, 840 150-kt warheads, 300 400-kt warheads, 400 750-kt warheads, and 78 1-Mt warheads. If 90% of either missiles or warheads are intercepted, remaining are 84×150 kt, 30×400 kt, 40×750 kt, 8×1 Mt. Since 10 PSI pressure would cause reinforced concrete buildings to collapse, destructive radius would be as follows:

• 150 kt: 2,35 km = 17,35 km2
• 400 kt: 3,25 km = 33,18 km2
• 750 kt: 4 km = 50,27 km2
• 1 Mt: 4,40 km = 60,82 km2

This means that a total area destroyed would be 4 950 km2. In the US, average urban density is 905 per square kilometer. This is a lowball estimate, since if urban areas are targeted, it would make sense to concentrate on the more densely populated area. Even so, the area destroyed would still lead to almost 4,5 million casualties.

Second, Hamas’ rockets are far easier to shoot down. They fly at flat arcs, and also fly very slowly due to their primitive construction. They also do not have any self-protection system. By comparison, ICBMs fly at speeds over Mach 20. While Hamas’ rockets are easily tracked and intercepted by radar, ICBMs are far more difficult, even before various self-defense systems are taken into account.

Third, the US missile defense system had been a distinct failure. It had been struggling to execute its testing plan, and what few tests had been conducted had produced rather troublesome results. Interceptors have hit their targets only about 50-60% of the time, and these tests had been carried out against only a small number of targets. These were also short-to-medium range missiles. When tested against long-range missiles, the system shot down 10 out of 18 targets. A 60% success rate would mean that, compared to the above calculations, there are 4 times as many unsuccessful intercepts – which means four times as many casualties, or almost 18 million (in reality, as noted, both low and high estimates would be much higher if missiles were targeted predominantly against high-density urban conglomerations).

Fourth, what tests there were of the US missile defense system highly exaggerated its capabilities. In a test, operators know where the warhead is coming from and when it had been launched. Neither of these would be known in the real war. Second, no US missile defense system had been tested against more than one target at a time.

Fifth, Iron Dome itself is unsuitable for the task. It can track and hit targets from a maximum range of 40 miles – which is far too late when intercepting an ICBM.

All of this together rather casts doubt onto the ability of the US missile defense program to perform its task.

• weapons