Still, there is an urgent antecedent question. What if the Iranian leadership did not meet the criteria of rational behavior in world politics? What if this leadership did not necessarily value Iran's national survival as a state more highly than any other preference, or combination of preferences?
In this scenario, admittedly unlikely, but not inconceivable, all "bets" on successful Israeli nuclear deterrence would be off. By definition, it could then become impossible to deter an irrational Iranian adversary with even normally credible threats of "massive retaliation" or "flexible response."
Nonetheless, Israel must continue to develop, test, and implement an Arrow-based interception capability to match the cumulative threat created by all enemy ballistic missiles. It must also take corollary and nuanced steps to enhance the credibility of its still "ambiguous" nuclear deterrent. More precisely, Israel must: (1) prepare to take its bomb out of the "basement" the moment that Iran crosses the final nuclear threshold; and (2) operationalize a recognizable second-strike nuclear force, one that is hardened and dispersed, and that is ascertainably ready to inflict an unacceptable retaliatory salvo against identifiable enemy cities. [See editorial cartoons about the Middle East uprisings.]
With regard to ending its historic position of deliberate ambiguity, IDF planners will first have to determine exactly how much disclosure would be purposeful and cost-effective. The point, of course, would not be to give up any essential Israeli nuclear secrets, but rather to ensure authoritative Iranian perceptions of both usable and penetration capable Israeli nuclear forces.
Israel must also make it clear to any would-be nuclear aggressor that Arrow defenses would always operate simultaneously or together with Israeli nuclear retaliations. In this connection, the prospective enemy state must be made to understand that Israel's Arrow deployment will never preclude, or render less probable, an intolerable Israeli nuclear reprisal.
In the best of all possible worlds, Iran, a party to the Nuclear Nonproliferation Treaty, would never have been allowed to proceed toward full and illegal nuclearization with impunity. Still, this is not yet the best of all possible worlds, and Israel will now have to deal capably with a persistently recalcitrant regime in Tehran by implementing a steady enhancement of its nuclear deterrence and active defense capabilities. Although changing the regime in Tehran might first appear to be an attractive alternative or supplementary security option, Jerusalem/Tel-Aviv should promptly understand that any such transformations would, even ideally, offer Israel only a temporary respite from catastrophic harms. It is also possible, perhaps even plausible, that regime change in Tehran could produce a more dangerous adversary. [See a slide show of 15 post-Cold War uprisings.]
There is one final important point concerning the growing Iranian nuclear threat. Soon, this unprecedented peril could be directed toward Israel not only via direct missile strike, but also by way of various low-tech delivery systems, operated by assorted terrorist surrogates. For example, if a newly-nuclear Iran should decide to share portions of its weapons-usable materials and scientific personnel with Hezbollah in Lebanon, Israel might then have to confront a greater likelihood of nuclear terrorism.
In principle, it is always in Israel's best interest to keep nuclear weapons and supporting infrastructures entirely out of all enemy hands. Still, Pakistan, coup-vulnerable and persistently unstable, is already nuclear, and Iran is almost certain, soon, to join the nuclear club.
Fully acknowledging these sobering facts, Israel must now systematically enhance and integrate its emergent nuclear deterrence postures with the nation's growing active defenses. This obviously complex effort should include, of course, pertinent cyber defenses. Critically, it should also be made appropriately recognizable to selected regional adversaries, and include certain carefully timed modifications of "deliberate nuclear ambiguity."