Doomsday: What could drive Israel and Iran to start launching nuclear weapons?

Although Israel’s Gaza war is most visibly being waged against Hamas, the ultimate adversary is Iran. If Israel’s counter-terrorism efforts should sometime bring it into direct confrontation with Iran, the result could be an immediate escalation between these two adversary states.

In such a plausible scenario, even a still-pre-nuclear Iran could elicit a “limited” Israeli nuclear reprisal. The principal escalation dangers would be an Iranian use of radiation dispersal weapons or an Iranian rocket attack on Israel’s Dimona nuclear reactor.   

For Israel, a country smaller than Lake Michigan, nuclear weapons and strategy remain essential to national survival. Israel’s traditional policy of deliberate nuclear ambiguity, or “the bomb in the basement,” goes back to its early days. During the 1950s, Prime Minister David Ben-Gurion understood the need for a dramatic “equalizer” against larger and more populous regional enemies.  

Today, facing a recalcitrant and soon-to-be nuclear Iran, Israel needs to update and refine its policy of deliberate nuclear ambiguity. The key objective of such needed changes would be credible nuclear deterrence, a goal that will now require selective nuclear disclosure. Though ironic and counter-intuitive, Iran will need to be convinced that Israel’s nuclear arms are not too destructive for actual use. 

There will be perplexing nuances. For Israel to fashion reason-based nuclear policies, Iran should be considered rational. But it is conceivable that Iran might act irrationally, perhaps even in alliance with other states (such as Syria or North Korea) or kindred terror groups (such as Hamas, Hezbollah, Palestinian Islamic Jihad or the Houthis).  

Unless Jerusalem were to consider Pakistan an authentic enemy, Israel presently has no already-nuclear enemies. Still, as an unstable Islamic state, Pakistan is potentially subject to a coup d’état by assorted Jihadist elements and is closely aligned with Saudi Arabia. The Sunni Saudi kingdom could sometime decide to “go nuclear” itself because of Shiite Iran’s steadily accelerating nuclear progress.

For Israel’s nuclear deterrence to work longer-term, Iran will need to be told more rather than less about Israel’s nuclear targeting doctrine and the invulnerability of Israel’s nuclear forces. In concert with such changes, Jerusalem will need to clarify its still-opaque “Samson Option.” The point would not be to “die with the Philistines” (per the biblical Book of Judges), but to enhance “high destruction” options of its nuclear deterrence posture. 

Though the only gainful purpose of Israel’s nuclear weapons should be deterrence at different levels of military destructiveness, there will remain circumstances under which Israeli nuclear deterrence could fail. How might such intolerable circumstances arise?  Four distinct scenarios emerge, with results that range from very destructive to catastrophic.  

First, if Iran were to launch “only” a massive conventional attack on Israel, Jerusalem could respond with a limited nuclear retaliation. If Iranian first-strikes were to involve chemical or biological weapons, Israel might also decide to launch a measured nuclear reprisal.

This decision would depend, in large part, on Jerusalem’s expectations concerning follow-on Iranian attacks and its calculations of comparative damage-limitation. A nuclear retaliation by Israel could be ruled out conclusively only in circumstances where the Iranian aggression is entirely conventional and “hard-target” oriented — that is, oriented toward Israeli weapons and military infrastructures, not toward Israel’s civilian populations. 

A second scenario would involve Israel feeling compelled to preempt Iranian aggression with conventional weapons. In that case, that enemy state’s response would largely determine Israel’s next moves. If this response were in any way nuclear, including “mere” radiological weapons, Israel would likely turn to certain controlled forms of nuclear counter-retaliation. If Iran’s retaliation were to involve other non-nuclear weapons of mass destruction, Israel could still feel pressed to take the escalatory initiative. This decision would depend upon Jerusalem’s considered judgment of enemy intent and on its corollary calculations of damage-limitation.  

If the Iranian response to Israel’s preemption were limited to hard-target conventional strikes, it is unlikely that Israel’s decision-makers would go nuclear. If, however, the Iranian conventional retaliation was “all-out” and directed in part toward Israeli civilian populations, an Israeli nuclear counter-retaliation could not be excluded. Such a counter-retaliation could be ruled out only if Iran’s conventional retaliation were proportionate to Israel’s preemption; confined to Israeli military targets; circumscribed by legal limits of “proportionality” and “military necessity,” and accompanied by verifiable assurances of non-escalatory intent. 

A third (and highly unlikely) scenario involves Israel launching a preemptive nuclear strike against Iran. Although circumstances could arise wherein such a strike would be rational and permissible under international law, it is improbable that Israel would allow itself to reach such end-of-the-line circumstances. An Israeli nuclear preemption could reasonably be expected only if Iran had already acquired nuclear or other weapons of mass destruction, threatened to use them, began a countdown to launch, and Jerusalem believed that exclusively conventional preemption could not save the Jewish State from destruction. 

A fourth scenario would be that of nuclear war fighting. This could occur if an Iranian nuclear first-strike or retaliation for an Israeli conventional first strike failed to destroy Israel’s second-strike nuclear capability, or vice versa.

For the time being, of course, any Iranian nuclear capacity would be limited to radiation dispersal weapons.

Louis René Beres is professor emeritus of International Law at Purdue University and author of “Surviving Amid Chaos: Israel’s Nuclear Strategy” (2018).