Nuclear deterrence is a game that even sane, rational governments may have to play, but there can be no assurance that enemies will always be rational. This presents a grave security problem, because the entire logic of nuclear deterrence rests squarely on the assumption that each state will always value its continued survival more highly than anything else. It follows that even a nuclear-weapons state able to destroy an aggressor after suffering an enemy first-strike attack could still lose the game.
A nuclear Iran is pretty much a fait accompli. For Israel, soon to be deprived of any remaining cost effective preemption options, this means forging a strategy to coexist with a nuclear Iran. This essential strategy of nuclear deterrence will call for reduced ambiguity about its strategic forces; enhanced and partially disclosed nuclear targeting options; substantial and partially disclosed programs for active defenses; recognizable steps to ensure the survivability of its nuclear retaliatory forces; and, to bring all these elements together, a comprehensive strategic doctrine.
In addition, because of the logical possibility of enemy irrationality, Israel's military planners must continue to identify suitable ways of ensuring that even a nuclear "suicide state" can be deterred. Such a perilous threat is very small, but it is not negligible. And although the probability of having to face such an irrational enemy state is low, the probable harm of any single deterrence failure could be intolerably high.
Israel Needs to maintain and strengthen its plans for ballistic-missile defense (the Arrow system), and also for Iron Dome, designed to guard against shorter-range rocket attacks. Still, these systems, including Magic Wand, which is still in the development phase, will inevitably have "leakage." Their principal benefit, therefore, must ultimately lie in enhanced deterrence rather than in any added physical protection.
For example, a newly-nuclear Iran, if still rational, would require steadily increasing numbers of offensive missiles to achieve a sufficiently destructive first-strike capability. Significantly, however, there could come a time when Iran will be able to deploy far more than a small number of nuclear-tipped missiles. Should that happen, Arrow, Iron Dome and, potentially, Magic Wand could cease their critical contribution to Israeli nuclear deterrence.
What if the leaders of a newly-nuclear Iran do not meet the expectations of rational behavior? What if this leadership does not consistently value Iran's national survival more highly than any other preference? In such unprecedented circumstances, Israel's leaders would need to look closely at two eccentric and more-or-less untried deterrence strategies, possibly in tandem with one another. First, they would have to understand that even an irrational Iranian leadership could have distinct hierarchies of preferences. Their task would be to determine precisely what these preferences might be (most likely, they would have to do with certain religious goals), and how these preferences are apt to be ranked in Tehran.
