Can Israel accept a nuclear Iran? The deterrence argument
In thinking about whether a system of deterrence/containment can be set up with a nuclear-armed Iran, it's important to understand what deterrence is and how it really works. So what is deterrence? Fundamentally, it's an exchange of information to establish stability without the need for actual physical combat. (The use of a threat to induce action is something else: "If you attack me I'll nuke you" is deterrence, but "Give me Schleswig-Holstein or I'll nuke you" is extortion.) In this context, I like to use the phrase "conversation of deterrence" to describe the exchange of information that is required to create stability.
The first element of this conversation of deterrence - the threat - is fairly well understood: if you carry out a particular class of act (the provocation), I will retaliate (the punishment). In order for a deterrent threat to be credible and effective, the deterring side needs to establish that is has both the capability and the will to carry out its threat under appropriate circumstances.
There is a "flip side" of a deterrent threat that is almost as vital as its credibility: an effective deterrent threat must be convincingly conditional. That is, just as it is vital to convey that you are willing and able to inflict punishment if someone does something you don't like, it is equally vital to convey that if the other side refrains from acting provocatively you will not punish. If punishment is not conditional in this way, it has little or no effect as a means of conditioning a desired behavior.
In unidirection deterrence - for example, in criminal law or between countries with vastly different military capabilities - the conversation of deterrence can end there, since threats flow basically in only one direction. However, in a system of mutual deterrence - which is what we're generally dealing with in the international-relations context - things are more complex, particularly when dealing with something like nuclear arms that have a massive impact in a very short time frame. Here we need a system of deterrence that forestalls not only provocation-and-punishment, but also preemption. Accordingly, the conversation of deterrence needs to convey not only the credibility and conditionality of the threat, but also the fact that the threat is understood and the condition accepted (even if grudgingly). The deterring power must be convinced that the other side understands and believes the deterrent threat, and will in fact be deterred; otherwise, the deterring power will have a strong motive to attack preemptively, since it cannot rely on its deterrent threat to create stability if it isn't sure that the other side is really deterred.
This goes even further: the deterred side must believe that its own acceptance of the conditions of deterrence is believed by the deterring side; in other words, it must have confidence that the deterring side has confidence in its deterrent, and thus will not attack preemptively. If you believe that you are likely to be attacked preemptively at some point, you have a strong motive to strike the first blow yourself - and this is exactly what creates instability instead of the stability that is the goal of a conversation of deterrence!
Of course, in a system of mutual deterrence, all these messages are exchanged (at least tacitly) in both directions. Each side knows that if it acts provocatively it will be severely punished, and that if it behaves itself, it will not be severely punished; and each side knows that a basically stable system of deterrence is in place, so that everyone can go on with life.
Now, here is the problem with containing/deterring Iran: a credible deterrent threat would probably prevent Iran from using nuclear weapons, as the Iranian regime does not have a record of irrational real-world behavior; however, there are factors that would make it very difficult to conduct an effective conversation of deterrence:
- There are some elements in Iran that might welcome nuclear war as part of their eschatological view of history. It's not completely clear how widespread such views are; there are experts (e.g. Bernard Lewis) who take this threat very seriously, and others who dismiss it out of hand. The problem is that if Israel believes that there is any significant probability that Iranian leadership might be willing (or even happy) to accept nuclear retaliation for a nuclear attack on Israel, Israel cannot have confidence in its deterrent; and, of course, if Israel lacks confidence in its deterrent, Iran cannot have confidence in Israel's confidence. Thus the conversation of deterrence would break down, and each side (particularly Israel) will have a strong motive to act preemptively. (It is important to remember, in this regard, that the heyday of U.S.-Soviet mutual deterrence was in the post-Kruschev era; when Stalin and Kruschev were in power, the U.S. had much less confidence in its deterrence because of its perception of Soviet ideology, and the system of deterrence very nearly broke down completely in the 1962 Cuban Missile Crisis. The mere physical fact of mutually-assured destruction does not ensure a successful conversation of deterrence!)
- To date, all nuclear powers have been essentially stable states with well-defined, relatively simple power structures. This means that conversations of deterrence could take place without the added impediment of uncertainty regarding whose finger would be on the button. (In this regard, the transition from Soviet Union to Russia can be judged a great success: the breakup of an empire is very seldom accomplished so peacefully, and the breakup of a nuclear-armed empire could have been disastrous. It is also worth noting that Pakistan has been stable so far - the potential for instability there is very worrisome, for many reasons.) In the case of Iran, there are multiple loci of power - the Presidency, the Supreme Ruler, the Revolutionary Guards, and others - and while the system has been effectively stable over recent years, there appears to be a high potential for severe instability in the future. This means that a system of deterrence involving Iran must encompass all these power loci, or at least the major ones. It is not very difficult to imagine a successful conversation of deterrence between Israel and Ayatollah Khamenei; but it is hard to imagine a successful conversation of deterrence involving, Israel, Khamenei, Mahmoud Ahmadinejad, their potential successors, the Revolutionary Guard, and others who might gain power in the near-to-medium-term future.
All this means that Israel cannot accept a "contained" Iran: there are simply too many impediments to a successful conversation of deterrence, and Israel would be forced to choose between a costly preemptive strike or an indefinite future of living in constant fear of nuclear attack.