Israel, Iran and Iron Dome

As advanced as Israel's rocket defense system is, it can not be the only thing to deter a nuclear Iran.

Arrow missile defense system 390 (photo credit: Israel Aerospace Industries/Reuters)
Arrow missile defense system 390
(photo credit: Israel Aerospace Industries/Reuters)
In the aftermath of Israel's Operation Pillar of Defense, considerable credit is being heaped upon Iron Dome. Technically, of course, such praise is warranted. Without a timely deployment of this advanced system of active defense, innocent Israeli populations could have suffered substantially greater harms.
What is not warranted, however, is a reflexive or visceral extrapolation from Pillar of Defense to the emerging nuclear threat from Iran. The threats are very different. This is because any system of active defense will inevitably have "leakage." This includes Iron Dome but also Arrow, the longer-range Israeli shield that would ultimately need to function against incoming Iranian missiles.
Although a less than 100% reliability of interception may be more-or-less acceptable in the face of shorter-range and exclusively conventional explosive rockets launched from Gaza, this less-than-total level of reliability could not be tolerable in the event of any WMD (chemical, biological, or nuclear) missile attack from Iran.
Plainly, in the very worst-case scenario of an Iranian long-range rocket attack bearing nuclear warheads, not even a single incoming missile could be allowed to reach its Israeli target. Yet, for the moment, at least, no conceivable system of active defense could assure such a conspicuously perfect level of protection.
For Israel, the core inference of this strategic limitation is the lack of wisdom in relying too heavily upon narrow technological solutions. Iron Dome, Arrow and the still in development, David's Sling (aka Magic Wand), can contribute mightily to Israel's defense and deterrence postures. But this contribution is less than a true panacea. Moreover, no system of missile defense could be of any use against Iran-assisted acts of nuclear terrorism.
Even after Pillar of Defense, Israel's remaining strategic options against a steadily nuclear-powered Iran must include preemption, or an expectedly unavoidable last-resort to defensive first strikes. Under relevant international law, if the nuclear danger posed by Iran were potentially existential, and also "imminent in point of time," these Israeli strikes could be appropriately justified as "anticipatory self-defense." Any such justification, going back to an 1837 case known in jurisprudence as "The Caroline," would be authoritatively consistent with customary international law.
These binding rules are identified at Article 38 of the Statute of the International Court of Justice.  Moreover, this critical consistency could be enlarged by Iran's ongoing and unhidden disregard for the Genocide Convention (1948), a foundational multilateral treaty that prohibits not only actual crimes against humanity, but also "conspiracy to commit genocide."
To be sure, because the human and material costs to Israel of any preemption against Iran would now be staggering, this option could only be rational in those cases where intelligence had reliably revealed an impending Iranian nuclear aggression.
In the final analysis, the correct strategic lesson to be drawn from Iron Dome's technical success, and also from the inherent limitations of all active defenses, is multi-faceted. Above all, Israel must prepare to do everything possible to deter an already-nuclear Iran, even if that country's core decision-makers were not expected to meet the standard tests of rationality in world politics. Here, even an Iranian leadership that would value certain religious preferences more highly than national survival could still be dissuaded from launching nuclear first-strikes against Israel. This would be accomplished by posing suitable threats to certain principal Iranian religious institutions and infrastructures.
More likely, however, the leaders of a nuclear Iran would remain subject to the usual threats of deterrence, threats based upon presumptions of rationality. With this in mind, Israel's task will also be to assure these leaders that any Iranian excursions into nuclear violence would unhesitatingly elicit at least parallel forms of nuclear reprisal. In this connection, it would be important to assure the Iranians that (1) Israel's nuclear weapons were not "merely" counterforce targeted; (2) these nuclear weapons were effectively invulnerable to enemy first-strikes; and (3) these weapons were fully capable of penetrating Iran's own active defenses.
To succeed with such assurances, Israel would have to take early steps at ending its longstanding posture of deliberate nuclear ambiguity, steps designed to begin to take the Israeli bomb out of the so-called "basement." By implementing very selective and partial moves toward nuclear disclosure, Israel could significantly enhance the credibility of its nuclear deterrence posture. Although counter-intuitive, the reason and rationality of any such implementation would be dictated by the primal need to convince Iran that Israel's weapons were both available and usable. Ironically, if Iran were to believe that Israel's nuclear weapons were "too large" or "too destructive," they might then become less subject to Israeli nuclear deterrence.
All of these essential enhancements of Israeli nuclear deterrence would have to be accompanied by apt forms of cyber-defense or cyber-war. There might also be some residual strategic benefit to Israel in exploring any still-remaining chances for regime change in Tehran. But this path could quickly prove to be a double-edged sword. There would be no assurances that any Iranian successor regime would necessarily turn out to be less jihadist, or more inclined to peace with Israel. For this successor regime, authentic diplomacy and negotiations could still be anathema.
Israel needs to continue with its impressive progress on diverse active defenses, especially Iron Dome, Arrow, and David's Sling. Under certain foreseeable circumstances, Israel could sometime be facing simultaneous rocket attacks from both assorted terror groups (Hamas in Gaza and Hezbollah in Lebanon), and belligerent states (Iran). With regard to any contemplated Iranian nuclear strike, Arrow's main function would not be limited to physical protection of otherwise unprotected Israeli noncombatants. Rather, where it is deployed to protect Israel's own "hard" nuclear targets, its corollary purpose would be to convince Iran that it can never hope to prevent an unacceptably destructive Israeli nuclear retaliation.
Taken together with improved nuclear deterrence and cyber-defense, Israel's active defenses represent an utterly indispensable component of the country's national security doctrine. Considered only by themselves, however, no matter how advanced and technically sophisticated, these defenses can never suffice.            The writer is Professor of Political Science and International Law at Purdue. The author of ten major books and several hundred journal articles on both strategic and jurisprudential matters, his columns appear regularly in many major newspapers and magazines. He was born in Zürich, Switzerland, on August 31, 1945.