If Iran Goes Nuclear: Missile Defense vs. Deterrence

There has been a lot of discussion in the media recently about the possibility of Iran obtaining nuclear weapons. I won't dive into the debate about whether or not Israel or the United States should attack Iran's nuclear facilities. Instead, I would like to write about the choices Israel will face if Iran does go nuclear.

Some have argued that the defenses required if Iran goes nuclear would bankrupt Israel's economy. Presumably, this defense refers to missile defenses and things like detectors at ports and border checkpoints. Such measures could indeed put a heavy strain on Israel's economy if implemented. But do they make sense?

Missile defense may be of limited use in a non-nuclear situation, but it is pointless in a nuclear one. Currently, Israel has to deal with regular rockets being launched from the Gaza Strip. Israel's deterrence of the militants launching these rockets is not absolute: They do not launch all the rockets they have or rarely launch full-on assaults of Israel; but there is a steady, low-level stream of rockets. Israel's current missile-defense system makes sense for protecting Israeli citizens against these every day non-nuclear rocket launches. Because Israel's deterrent strategy does not rely on launching rockets for rockets, there is minimal risk of escalation. This does not mean no risk at all: Militants could launch rockets directly at Sderot with a domestic (i.e. Palestinian) audience in mind with the expectation that the rockets will be stopped anyway. Perhaps the goal would be just to cost Israel money by forcing it to launch expensive interceptor rockets. If any Gazan rockets get through, however, an Israeli counterstrike could be imminent. However, this is not really all that different from the situation without the missile-defense shield, as rockets do sometimes hit civilians obliging Israel to hit back. On balance, the shield therefore seems to make sense.

At the same time, however, such a shield could never be expected to provide any real defense against a heavy onslaught. The number of interceptor rockets is limited, interception is not 100% assured, and Israel's interceptor rockets are vastly more expensive than the rockets militant groups launch from the Gaza Strip. A launch of hundreds of rockets from the Gaza Strip could therefore easily overwhelm the system. Such a system is no good at providing 100% security.

This is also the reason why a missile shield against nuclear missiles makes no sense. In a nuclear situation, prevention must be absolute. One nuclear-tipped missile getting through is too many. There are two reasons given why missile defenses don't make sense. The first is that they do not work, the second is that they can lead to instability, undermining deterrence. Both of these propositions cannot be true at the same time. If missile defenses don't work, then there is no reason that they should cause instability. If they cause instability, then they must work somehow or other. Even so, it is possible that both these propositions could be true at different times. This is the reason why it's plausible that politicians might build an expensive and ultimately ineffective missile-defense system.

During an initial phase, Iran might not have very many nuclear missiles. It might therefore seem feasible to stop two, three, or four missiles using a high-tech missile defense shield. It would be expensive, but it would almost seem to make sense. If this shield is seen as solid enough by Iran, it could very well lead to instability via an arms race. Iran would recognize that the way around the missile shield is to build enough nuclear missiles to overwhelm it. If Israel tries to keep up, this would be very expensive indeed. All of this could only occur, however, if both sides focused blindly on missiles. There is always the possibility of smuggling a nuclear bomb into a country by other means and this seems even harder to rule out altogether.

During the second stage, a missile defense system is less likely to cause instability or a further arms race because it will become increasingly clear that it cannot be effective. It would always be possible to overwhelm the system and, because such a system could never be 100% reliable, it would always be possible to make sure that one missile (and that is all that is required) would get through. The level of control required to seal off all of Israel's borders and to provide an ultimately incredible degree of reliability from the missile-defense system would turn Israel into a police state and be staggeringly expensive.

All of this suggests that the best move is to rely on deterrence and not bother with missile-defense for nuclear missiles. To do this, Israel may need to make its presumed nuclear capability explicit and more transparent. Deterrence may also not be 100% safe, but as I have illustrated, missile-defense would not increase that security in the slightest. Given (at best) equal levels of security, it seems obvious to me that leaders should choose deterrence due to its lower cost and the smaller number of restrictions that would have to be placed on Israelis' civil liberties. Neither of these situations may be desirable, and leaders might like to look like they're doing something (whereas deterrence might look like doing nothing). When that something is surely ineffective, expensive, and heavily restricts civil liberties, however, there is not really much of a choice at all.


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