Even an irrational leadership could be subject to threats of deterrence that credibly threaten certain deeply held religious as well as public values. The difficulty for Israel, is to ascertain, the precise nature of these core enemy values. Should it be determined that an Iranian leadership were genuinely "crazy" or "mad," that is, without any decipherable or predictable ordering of valued preferences, deterrence bets could have to give way to preemption.
Such determinations are strategic, rather than jurisprudential. From the discrete standpoint of international law, especially in view of Iran's expressly genocidal threats against Israel, a preemption option could still represent a permissible expression of anticipatory self defense. Again, this purely legal judgment would be entirely separate from any parallel or coincident assessments of operational success.
Chaotic instability in the Middle East heightens the potential for expansive wars. The "Arab Spring," Iranian nuclearization, and Palestinian statehood, singly, and in synergy with each other, augur badly for Israel's long-term security interests. To counter this still-evolving hazard, Israel must do many things, simultaneously, on the political, diplomatic and military fronts. From the strategic perspective, in particular, it must, among other refinements, prepare immediately to modify or abandon its long-standing policy of deliberate nuclear ambiguity.
As we have already noted earlier, to meet unprecedented existential threats, Israel must finally acknowledge the timeless warning of Karl von Clausewitz. In certain more-or-less residual strategic circumstances, such acknowledgment would instruct, "mass counts."
By itself, removing Israel's bomb from the basement will not immediately ensure the success of the imperiled country's indispensable nuclear deterrent. Nonetheless, in the not-too-distant future, this strategy would still present a strongly-preferred security option to any continued posture of deliberate nuclear ambiguity.