“The Highest Law”: Israel, Iran, and Anticipatory Self-Defense -A Memorandum for the Prime Minister

by Louis René Beres (Ph.D., Princeton, 1971), Emeritus Professor of International Law I Purdue University

Abstract: “The safety of the people,” declares Cicero in The Laws, “is the highest law.”

For Israel, this sentiment has always made sense, but never more than after the October 7, 2023 Hamas terror attacks. Now, because Iran (1) is Hamas’s dedicated state sponsor; (2) is continuing on its single-minded path to nuclear weapons status; and (3) is engaged in intermittently direct conflict with Israel, Jerusalem will need to focus on plausibly effective preemption options. If Israel should decide that it no longer has any reasonable alternative to launching appropriately defensive attacks against specific high-value military/industrial targets in Iran, this non-nuclear strike would need authoritative justifications under binding international law. In the following essay, Professor Louis René Beres, who was Chair of Project Daniel (Israel, PM Sharon, 2003-2004), analyzes Israel’s right and capacity to act in “anticipatory self-defense” against Iran, a near-nuclear state adversary. Prima facie, the Islamic Republic of Iran is a continuously law-violating foe that (4) openly supports jihadist terror against Israeli noncombatants; and (5) openly acknowledges genocidal intentions.

Background of Current Crisis: Israel, Iran and the “State of Nature”

To fully understand what is happening between Israel, Iran and mutually reinforcing Islamic terrorist groups, especially Hezbollah in Lebanon, all conflicting policies should be examined “in context.” Accordingly, world politics remain in a “state of nature,” a condition that earlier political philosophers had also called a “state of war.”[i] By definition, within such continuous anarchy[ii] – a bellum omnium contra omnes or “war of all against all” – international law[iii] is often compelled to operate in “vigilante” form. In more expressly legal terms, this “Westphalian” dynamic describes a “self-help” system of national security and global power management.[iv]

In understanding these matters, clarity ought not to be expected. The threat-based Westphalian system remains dense and bewildering. After all issues have been checked and counter-checked, there would remain assorted caveats and nuances for Israeli analysts and defense planners to consider. Regarding Israel, Iran and preemption, though codified norms don’t usually allow states to strike first in self-protection, the customary law of nations does permit certain residual acts of “anticipatory self-defense.”[v]

Under such binding law, defensive first strikes or acts of “preemption” could be considered permissible in particular security-threatening circumstances. But if such resorts to anticipatory self-defense could be lawful or even law-enforcing, they could still prove unreasonably dangerous (not cost-effective), strategically misconceived or tangibly ineffectual. Israel, therefore, should always evaluate its anticipatory self-defense options along two principal standards of evaluation.

What would be the implications of such evaluations for Israel, a nuclear state increasingly imperiled by a nuclearizing state adversary?[vi] Before Israel could decide rationally to invoke a calculated strategy of preemption vis-à-vis Iran, its pertinent policymakers, and strategists would need to assess this strategy according to overlapping considerations of law and security.

What does this all mean for impending national security decision-making in Jerusalem? At some point, Israel could calculate that a considered preemptive strike against selected hard Iranian targets (i.e., weapons/weapon-system infrastructures) would be convincingly legal, but still not “work.” Alternatively, Jerusalem could conclude that any such considered strike would be promising or gainful in operational war-fighting terms, but simultaneously more-or-less illegal.

What then?

There would be further questions. For Israel, a country smaller than America’s Lake Michigan, one neglected danger of waiting too long is that Tehran could more easily implement protective measures that would pose additional hazards. Deigned to guard against an Israeli preemption, such Iranian measures could involve the attachment of “hair trigger” launch mechanisms to nuclear weapon systems and/or the adoption of “launch on warning” policies, possibly coupled with variously ambiguous pre-delegations of nuclear launch authority.

Even in the absence of such prospective threats, a newly-nuclear Iran could calculate at any time that striking first would be its only rational strategic option. It follows, among other things, that the obligatory search for “escalation dominance” during a military crisis would favor an already-nuclear Israel, but only if Iran itself were not yet nuclear. Ipso facto, a continuation of the now-prevailing nuclear asymmetry between these two adversartial states could be indispensable to Israel’s literal survival.

What Would Constitute a Lawful Preemption?

Optimally, Israel would do everything possible to prevent any out-of-control struggle for escalation dominance. The principal argument here for special Israeli prudence would involve corollary and not insignificant risks of accidental or unauthorized attacks against Israeli armaments or civilian populations.[vii] Nonetheless, if such a struggle were ever to become a fait accompli, Jerusalem could still calculate, correctly, that a preemptive strike would be both lawful and necessary. In part, this consequential judgment would owe to the following reasoning in Jerusalem: Any expected Iranian retaliation, however damaging, would still be more tolerable than the plausibly expected consequences of Iranian first-strikes.

For the moment, though these enemy first-strike aggressions would be conventional or non-nuclear, they could still include radiation dispersal weapons, an attack on Israel’s nuclear reactor at Dimona, or even surrogate nuclear attacks launched by Iran’s already-nuclear ally, North Korea. Regarding Pyongyang and Kim Jung Un, it ought to be remembered that it was North Korea that built a nuclear reactor for Syria at Deir al-Zour. This reactor was destroyed by an Israeli preemptive attack in 2007. North Korea, of course, now has growing military ties to Russia

In its present legal and physical form, Israel, which “began” in 1948,[viii] will last only as long as its leaders remain attentive to Cicero’s primal warning about national “safety.”[ix] Says the ancient Roman jurist in The Laws: “The safety of the People shall be the highest law.” Such needed attentiveness could be fully consistent with the authoritative expectations of international law.[x]

International law is never a suicide pact. Israel’s basic security problems with Iran could compel Jerusalem to decide once again between waiting for an enemy to strike first[xi] or striking first itself. When judged from a strategic and tactical perspective, the choice of a preemption option could sometimes be rational and cost-effective for Israel.[xii]

Under binding international law, preemption might also represent a permissible option. In this connection, though subject to important constraints and conditions, the right of “anticipatory self-defense” is already well established in relevant jurisprudence.[xiii]

An Israeli Decision to Preempt

What does the ascertainable convergence of strategic and jurisprudential assessments of preemption say about Israel’s prospective calculations on striking first against Iran? It suggests, among other things, that Israel need not be deterred from undertaking security-maximizing forms of preemption out of fear that its actions would be described as criminal.[xiv] Although a substantial number of states would condemn Israel for “aggression”[xv] under virtually any circumstances, this particular charge – so long as Israel’s preemptive strikes met the expectations of jus ad bellum (justice of war) and jus in bello (justice in war)[xvi] – could be countered authoritatively by informed references to international law.

In jurisprudence, as in other disciplinary realms, history deserves an evident pride of place. The right of self defense by forestalling an attack appears in Hugo Grotius’ Book II of The Law of War and Peace in 1625.[xvii] Recognizing the need for “present danger” and threatening behavior that is “imminent in a point of time,” Grotius indicates that self defense is to be permitted not only after an attack has been suffered, but also in advance, that is, “where the deed may be anticipated.”[xviii] Or, as he explains a bit further on in the same chapter, “It be lawful to kill him who is preparing to kill….”[xix]

A similar position was taken by Emmerich de Vattel. In Book II of The Law of Nations (1758), Vattel argues: “The safest plan is to prevent evil, where that is possible. A Nation has the right to resist the injury another seeks to inflict upon it, and to use force and every other just means of resistance against the aggressor. It may even anticipate the other’s design, being careful, however, not to act upon vague and doubtful suspicions, lest it should run the risk of becoming itself the aggressor.”[xx]

Grotius[xxi] and Vattel parallel the Jewish interpreters, although the latter speak more generally of interpersonal relations than about international relations. Additionally, the Torah contains a prominent provision exonerating from guilt a potential victim of robbery with possible violence if, in self defense, he struck down and if necessary even killed the attacker before he committed any crime. (Ex. 22:1). In the precise words of the rabbis, “If a man comes to slay you, forestall by slaying him!” (Rashi; Sanhedrin 72a).

Both Grotius and Vattel caution against abusing the right of anticipatory self defense as a pretext for aggression,[xxii] but this is an abuse that Israel, in its current relationship with Iran, could commit. As Iran seemingly considers itself in a condition of war with Israel, any Israeli preemption against this nuclearizing adversary would represent not an act of anticipatory self-defense, but rather one more military operation in an ongoing or protracted war. It follows further in such circumstances that the Israeli military operation’s legality[xxiii] would have to be appraised in terms of its apparent conformance or nonconformance with the relevant laws of war of international law (jus in bello).[xxiv]

Jurisprudentially, to identify any such operation as an act of aggression against another state that already considered itself at war with Israel, would be nonsense.[xxv]

Background of Preemption in Law

Even if Iran were not in a condition of belligerence with the Jewish state, a condition amplified periodically by Tehran’s open calls for Israel’s destruction,[xxvi] and tangibly by Iran’s April indiscriminate missile attacks on Israeli civilians, an Israeli preemptive action could be law-enforcing. Israel, in the fashion of every state under world law, is peremptorily entitled to existential self-defense. Today, in an age of uniquely destructive weaponry, international law does not require Israel or any other state to expose its citizens to atomic annihilation.[xxvii]

The right of self-defense, we learn from Emmerich de Vattel, gives rise to the “right to resist injustice.” According to the Swiss scholar’s argument at Chapter V of the Law of Nations, or the Principles of Natural Law (1758), “On the Observance of Justice between Nations:”

Justice is the foundation of all social life and the secure bond of all civil intercourse. Human society, instead of being an interchange of friendly assistance, would be no more than a vast system of robbery if no respect were shown for the virtue which gives to each his own. Its observance is even more necessary between Nations than between individuals, because injustice between Nations may be followed by the terrible consequences involved in an affray between powerful political bodies, and because it is more difficult to obtain redress…. An intentional act of injustice is certainly an injury. A Nation has, therefore, the right to punish it…. The right to resist injustice is derived from the right of self-protection.[xxviii]

The customary right of anticipatory self defense has its modern origins in the Caroline incident, an event that concerned the unsuccessful rebellion of 1837 in Upper Canada against British rule (a rebellion that aroused sympathy and support in the American border states).[xxix] Following this landmark event, the serious threat of armed attack has generally been taken to justify a state’s militarily defensive action. In an exchange of diplomatic notes between the governments of the United States and Great Britain, then U.S. Secretary of State Daniel Webster outlined a framework for self defense which did not require an actual attack.[xxx] Here, military response to a threat was judged permissible so long as the danger posed was “instant, overwhelming, leaving no choice of means and no moment for deliberation.”[xxxi]

In certain distinctly residual circumstances, permissible forms of anticipatory self-defense could be expressed via assassination/targeted killing (although classical philosophical and jurisprudential arguments supporting assassination are usually cast more narrowly in terms of a tyrannicide motif).[xxxii] Representing an alternative or addition to standard military forms of preemption, such targeted killing,[xxxiii] in order to be consistent with appropriate international legal expectations, would need to be undertaken when the danger posed to Israel actually met the specific test of the Caroline. Accordingly, if the targeted killing were undertaken only to destroy the potential threat of an enemy, i.e., as a preventive action, it would not qualify as permissible in law.

If, however, the assassination were undertaken in anticipation of some immediate enemy aggression, i.e. as a preemptive action, it could still qualify as “anticipatory self-defense.”[xxxiv]

There are several antecedent problems. First, in the “real world,” judgments concerning the immediacy of anticipated aggression are exceedingly difficult to make. Second, even where such judgments are ventured, it can never by altogether clear whether the degree of immediacy is sufficient to invoke preemption rather than prevention. Third, in meeting the legal requirements of defensive intent, a state may have to act preventively rather than preemptively, because waiting to allow a threat to become more immediate could have decisively or even intolerably negative strategic/tactical consequences. And fourth, the actual state-preserving benefits that might accrue from the assassination of enemy leaders are apt to be contingent upon not waiting until the danger posed is “instant, overwhelming, leaving no choice of means and no moment for deliberation.”

Some scholars argue that the customary right of anticipatory self defense articulated by the Caroline has been overridden by the specific language of Article 51 of the UN Charter.[xxxv] In this view, Article 51 fashions a new and more restrictive statement of self defense, one that relies on the literal qualification contained at Article 51, “….if an armed attack occurs.” Still, this interpretation ignores that international law cannot compel a state to wait until it absorbs a devastating or lethal first strike before acting to protect itself.[xxxvi]

Recalling Cicero: “The safety of the People shall be the highest law.”

There is more. The argument against a more restrictive view of self-defense is reinforced by the evident weaknesses of the U.N. Security Council in offering collective security against an aggressor. Both the Security Council and the General Assembly refused to censure Israel for its 1967 preemptive attack against certain belligerent Arab states. This refusal signified implicit approval by the United Nations of Israel’s 1967 resort to anticipatory self defense.[xxxvii]

Before Israel could persuasively argue any future instances of anticipatory self-defense under international law, a verifiable case would have to be made that Jerusalem had first sought to exhaust all available means of peaceful settlement. To wit, even a broad view of anticipatory self defense cannot relieve a state of this peremptory obligation, codified inter alia at Article 1 and at Article 2(3) of the UN Charter.[xxxviii] Strictly speaking, these obligations should not actually be binding upon Israel because of the de facto condition of belligerency created and sustained by Iran,[xxxix] but the global community generally seems to have ignored these conditions.

Jewish-Historical Background and Future Genocide Against Israel

Interestingly, certain origins of pertinent legal considerations would have their conceptual roots in ancient Israel. According to Grotius, citing to Deuteronomy in The Law of Prize and Booty, the Israelites were exempted from the issuance of warning announcements when dealing with previous enemies (what we might reference today as an ongoing or protracted war, precisely the condition that currently obtains between Israel and Iran.) The Israelites, recounts Grotius, had been commanded by God to “refrain from making an armed attack against any people without first inviting that people, by formal notification, to establish peaceful relations ….” “Yet,” he continues, “the Israelites…

thought that this prohibition was inapplicable to many of the Canaanite tribes, inasmuch as they themselves had previously been attacked in war by the Canaanites.”

“Hence,” says Grotius, “we arrive at the following deduction”:

Once the formality of rerum repetitio [request of restitution or reparations] has been observed, and a decree on the case in question has been issued, no further proclamation or sentence is required for the establishment of that right which arises in the actual process of execution. For in such circumstances [and this is especially relevant to the modern State of Israel] one is not undertaking a new war but merely carrying forward a war already undertaken. Thus the fact that justice has once been demanded and not obtained, suffices to justify a return to natural law.[xl]

What about an Iranian genocide against Israel? Genocide is a word with very precise jurisprudential meaning. Codified at the Genocide Convention, a treaty [xli] that entered into force on January 12, 1951, it means any of a series of stipulated acts “committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group as such….” The key to understanding and identifying genocide lies in the phrase, “intent to destroy.” Accordingly, a genocidal state must display “criminal intent” or mens rea.

Outside of Iran, active support in parts of the Arab world for genocide against “The Jews” is a matter of long historical record. Even before creation of the State of Israel, such support was displayed proudly and enthusiastically during the Holocaust. On November 28, 1941, the Grand Mufti of Jerusalem, Haj Amin, met in Berlin with Adolph Hitler. The purpose of this meeting, which followed Haj Amin’s organization of SS troops in Bosnia, was to ensure cooperation on “The Jewish Question.” It was necessary, Haj Amin insisted, that all Jews be deported to countries “where they would find themselves under active control, for example, in Poland, in order thereby to protect oneself from their menace and avoid the consequent damage.”[xlii]

Neither Palestine’s “Non-Member Observer State” nor already-sovereign Arab states have ever publicly criticized the Mufti’s lascivious support for Holocaust crimes. During the 1950s and 1960s, Adolph Hitler remained an enormously popular figure in the Arab world. Unsurprisingly, responses in this region to the Eichmann trial in Jerusalem (1961) generally treated the mass murderer as a “martyr,” and congratulated the Nazi war criminal for having “conferred a real blessing on humanity” by enacting a “final solution.”[xliii] vs. “counterforce” military objectives.

In making its nuclear choices, Israel will have to confront a paradox. Credible nuclear deterrence,[xlviii] essential to security and survival in a world made more dangerous by the creation of Palestine,[xlix] would require “usable” nuclear weapons. If these weapons were obviously inappropriate for any reasonable objective, they would not deter.

All things considered, Israel, if confronted by a new state of Palestine, would be well-advised to do everything possible to prevent a nuclear Iran, possibly including variously cost-effective non-nuclear preemptions. Under these portentous conditions, Israel would require a very believable (and hence usable) nuclear deterrent, one that could be employed without igniting “Armageddon” for regional belligerents and that could serve damage-limiting military purposes (whatever the collateral effects) against Iranian weapons (nuclear and non-nuclear) should deterrence fail.

Creation of a fully-sovereign Palestine could have a dramatic effect on Jerusalem’s decisions concerning anticipatory self-defense. Israel’s extant nuclear weapons status and strategy would impact and influence this vital decision. More precisely, should Israeli decision-makers determine that the country’s nuclear weapons could support preemption by deterring Iran from retaliating, this “atomic factor” could encourage Israeli defensive first strikes. If, on the other hand, Jerusalem were to calculate that Iran or (in the future) other prospective target states would be unimpressed by any threats of an Israeli nuclear counter-retaliation, this variable would likely not encourage defensive first strikes.

Israel’s Nuclear Strategy and Law-Based Preemptions

Could the precise form of Israel’s nuclear strategy make a difference in shaping these circumstances? Relying upon nuclear weapons not to deter Iranian first strikes, but to support its own preemptive attacks, Israel would have to choose between continued nuclear ambiguity (implicit threats) and nuclear disclosure (explicit threats). How should it choose?[l]

More than anywhere else, the answer lies in Jerusalem’s confidence that its adversaries already acknowledge Israel’s “calibrated” nuclear capability. Should this confidence be high, there could still be variously compelling valid reasons to take the bomb out of the “basement.” If such confidence were low, the move to disclosure would likely be even more purposeful, because any critical reactions by the United States would be less worrisome for Israel in the “Cold War II” strategic environment.[li]

What about Afghanistan? On its face, the fall of that “graveyard of empires” revealed no verifiably direct connections to Israel’s national security. Nonetheless, the overwhelming defeat of its American patron in that volatile region could have significant “spillover effects” for Israel. Most worrisome, in this regard, would be emboldened sub-national Islamist adversaries (e.g., Sunni Hamas, Shiite Hezbollah, ISIS-K); expanded strife between pertinent enemies and unstable states (e.g., Taliban vs. ISIS-K); and additional geo-strategic influence for the already-nuclear Islamic state of Pakistan). This last result would likely elicit certain “countervailing” reactions from India and/or China, reactions that could never be ignored by Vladimir Putin’s Russia.

In view of what is generally believed throughout the Middle East and the wider world, there is every good reason to assume that Israel’s nuclear arsenal does exist and that it could be “nuanced” to meet the strategic particularities of any specific threat. Israel’s inter-linked enemies already share this key assumption and need no further convincing about Jerusalem’s basic nuclear capacities. The most critical questions about Israel’s nuclear deterrent would not be about capability, but about willingness. How likely is it that Israel, after launching non-nuclear preemptive strikes against enemy hard targets, would respond to enemy reprisals with some sort nuclear counter-retaliation?

These are all bewildering matters. What will Israeli planners conclude? The answer depends in part upon their view of Iran’s expectedly reciprocal judgments concerning Israel’s pertinent leaders. Do these judgments suggest a leadership that believes it can gain the upper hand with nuclear counter-retaliation? Or do they suggest a leadership that believes such counter-retaliation would bring upon Israel intolerable levels of adversarial harm?

Depending on the way in which enemy decision-makers in Tehran interpret Israel’s authoritative perceptions, they will accept or reject the cost-effectiveness of launching a non-nuclear retaliation against Israel. This implies that it is in Israel’s best interest to communicate the following strategic assumption to its Iranian enemy: Israel would be acting rationally

“Palestine” and Iran

Overall, the complex security situation is fraught not only with unprecedented danger,[xliv] but also with considerable irony. Before Israel could seriously begin to move toward accepting Palestinian sovereignty and independence, toward a “two-state solution,” an Iranian regime preparing for genocidal war against Israel would have to reverse such preparations. This is because Israel could not afford to confront the existential risks of another hostile Islamic state on its borders.[xlv]

In the absence of such peace-centered movement in Iran, the creation of Palestine could meaningfully affect Israel’s inclination to preempt against Iran. Because of Israel’s small size and corresponding lack of “strategic depth,” its inclination to strike first at Iranian hard targets could then become especially high. Deprived of strategic depth, Israel could not hold out for as long as was possible when Palestine was still merely an “Authority” or “UN Non-Member Observer State.”

There is more. It is plausible that a post-Palestine shift in Israeli nuclear strategy from deliberate ambiguity to disclosure[xlvi] could reduce Israel’s incentive to preempt, but only if Jerusalem had first been made to believe that its nuclear deterrent threat was being taken with sufficient seriousness by Iran.[xlvii] Several corollary problems would be considered.

First, how would Israel’s leadership know that taking the bomb out of the “basement” had actually enhanced its nuclear deterrence posture? To a certain extent, the credibility of Jerusalem’s nuclear threats would be contingent upon the severity of different provocations. It might be believable if Israel were to threaten nuclear reprisals for provocations that endanger the physical survival of the state, but it would almost certainly be less believable to threaten such reprisals for relatively minor territorial infringements or incursions. One “grey area” provocation could involve any growing Iranian threat to use radiation dispersal weapons, an option that might be combined with Iranian rocket attacks on Israel’s nuclear reactor at Dimona.

There would be other problems and complexities. To function successfully, Israel’s deterrent, even after being removed from the “basement,” would have to be rendered secure from Iranian preemptive strikes. Israel must also remain wary of “decapitation,” of losing the “head” of its military command and control system, because of enemy first-strike aggressions. Should Israel’s enemies be unpersuaded by Jerusalem’s conspicuous move away from deliberate ambiguity, – a move intended to strengthen Israel’s nuclear deterrent – they might then initiate such strikes as could immobilize Israel’s order of battle.

What then?

A contrary argument about the effects of Palestine on Israel’s inclination to preempt suggests that because of Israel’s newly expanded vulnerability, its nuclear deterrent could become more credible than before. As a result, Jerusalem could better afford not to strike first than when it still needed to administer terror-spawning Palestinian territories. In this situation, the principal benefit of shifting from ambiguity to disclosure would lie in an explicitly-identified “escalation ladder,” a metaphor revealing a broad array of feasible Israeli reprisals. These would range from limited conventional responses to calibrated nuclear strikes.

In weighing different arguments concerning the effect of Palestine upon an Israeli preemption, particular attention would need to be directed toward Israel’s presumptions about the inevitability of war with Iran and its longer-term expectations for Iranian vulnerability. Should Israel’s leaders conclude that the creation of Palestine would make major war with Iran more-or-less inevitable, and that, over time, Iranian vulnerability to Israel would likely diminish, Jerusalem’s inclination to strike first could reasonably be increased. To a certain extent, Israel’s tactical judgments on preemption will be affected by antecedent decisions on nuclear strategy, including decisions concerning “counter value” by responding to enemy non-nuclear reprisals to Israeli preemptive attacks with a nuclear counter-retaliation. The plausibility of this assumption could be enhanced considerably if the Iranian reprisals were to involve chemical and/or biological weapons.

All of these calculations assume rationality. In the absence of calculations that compare the costs and benefits of strategic alternatives, what will happen in the Middle East must always remain a matter of whimsy or conjecture. The prospect of non-rational judgments in the region is always high, especially as the influence of Islamist/Jihadist ideologies remain strongly determinative among Iranian decisional elites.

To the extent that Israel might one day believe itself confronted with non-rational state enemies, particularly ones with highly destructive weapons in their arsenals, its incentive to preempt could become overwhelming. In fact, should such enemies ever be believed to hold nuclear weapons,[lii] Israel might even decide rationally to launch a nuclear preemption against these enemy arsenals. This would appear to be the only calculable circumstance in which a rational Israeli preemptive strike could ever be nuclear.

Iran should understand from this that there are foreseeable conditions wherein Jerusalem might decide to actually launch its nuclear weapons. In essence, these conditions would concern the dissembling prospect of a total military defeat.[liii] Faced with imminent destruction of the Jewish State, Israel’s leaders would almost certainly do whatever is needed to survive, including resort to nuclear retaliation, nuclear counter-retaliation, nuclear preemption or (most “residual” of all) nuclear war-fighting.

Nuclear Retaliation

Should Iran launch a nuclear first-strike against Israel, Jerusalem would certainly respond, to the extent possible, with a nuclear retaliatory strike. If this enemy’s first-strikes were to involve other forms of unconventional weapons, i.e., chemical and/or biological weapons, Israel might launch a nuclear reprisal, depending, in large measure, upon Jerusalem’s expectations of follow-on aggression and on its associated calculations of comparative damage-limitation. If Israel absorbed a massive conventional attack, a nuclear retaliation could not automatically be ruled out, especially if: (a) the aggressor were perceived to hold nuclear and/or other unconventional weapons in reserve; and/or (b) Israel’s leaders were to believe that non-nuclear retaliations could not prevent destruction of the Jewish state. A nuclear retaliation by Israel could be ruled out only in those circumstances where Iranian enemy aggression were clearly conventional, “typical” (i.e., consistent with previous instances of enemy attack, in both degree and intent) and determinably hard-target directed.

Nuclear Counter Retaliation

Should Israel feel compelled to preempt Iranian enemy aggression with conventional weapons, the Iranian response would largely determine Jerusalem’s next moves. If this response were in any way nuclear, Israel would most assuredly resort to nuclear counter-retaliation. If this retaliation were to involve chemical and/or biological weapons, Israel might also feel pressed to take the escalatory initiative – again, depending upon Jerusalem’s considered judgments of enemy intent and its calculations of essential damage-limitation.

Should the Iranian response to Israel’s preemption be limited to hard-target conventional strikes, it is unlikely that Jerusalem would move on to nuclear counter-retaliations. If, however, the enemy conventional retaliation was all-out and directed toward civilian populations as well as to military targets, an Israeli nuclear counter-retaliation could not be ruled out ipso facto. It would appear that such a counter-retaliation could be ruled out only if the enemy conventional retaliation were ascertainably proportionate[liv] to Israel’s preemption, confined exclusively to Israeli hard-targets, circumscribed by the jurisprudential limits of “military necessity” [lv] and accompanied by variously explicit assurances of non-escalatory intent.

Nuclear Preemption

It is highly unlikely (perhaps inconceivable) that Israel would ever decide to launch a preemptive nuclear strike. Though strategic circumstances could arise wherein such a strike would be determinably rational (i.e., the calculated prospective benefits of the strike would outweigh prospective costs), it is implausible that Israel would ever allow itself to reach such “end-of-the-line” alternatives. Moreover, unless the nuclear weapons involved were used in a fashion consistent with authoritative expectations of the laws of war – the limits of “discrimination” (aka “distinction”); “proportionality” and “military necessity” – this form of preemption would represent an egregious violation of international law prima facie.

Even if such consistency were possible, the psychological/political impact of this activity on the world community would be negative and far-reaching. It follows that an Israeli nuclear preemption could be expected only: (a) where Israel’s Iranian enemies had acquired nuclear and/or other unconventional weapons judged capable of destroying the state; (b) where these enemies had made clear that their intentions paralleled their capabilities; (c) where these enemies were believed ready to begin a “countdown to launch;” and (d) where Jerusalem believed that Israeli non-nuclear preemptions could not achieve the needed minimum levels of damage-limitation, i.e., levels consistent with physical preservation of the polity.

Nuclear Warfighting

Should nuclear weapons ever be introduced into conflict between Israel and Iran, either by the Jewish State or by the Iranian foe, nuclear war-fighting, at one level or another, would ensue. This would hold true as long as: (a) enemy first-strikes against Israel would not destroy Jerusalem’s second-strike nuclear capability; (b) enemy retaliations for Israeli conventional preemption would not destroy Jerusalem’s nuclear counter-retaliatory capability; (c) Israeli preemptive strikes involving nuclear weapons would not destroy Iranian second-strike nuclear capabilities; and (d) Israeli retaliation for enemy conventional first-strikes would not destroy Iranian nuclear counter-retaliatory capability.

It follows from Israel’s strategic requirements that Jerusalem should do whatever is needed to ensure the likelihood of (a) and (b) above, and the unlikelihood of (c) and (d). This means, among other things, strengthening the hard-target kill capacity of its recognizably survivable and penetration-capable nuclear forces.

What, exactly, would a nuclear war “mean”? Even the most limited nuclear conflict would signal genuine catastrophe.[lvi] Just the immediate effects of the explosions; thermal radiation, nuclear radiation, and blast damage, could cause intolerably wide swaths of death and devastation.

None of this is meant to suggest that an Israeli conventional defensive first-strike would raise the likelihood of a nuclear war. To the contrary, Israel’s resort to a non-nuclear preemption might sometime represent the optimal way to prevent a nuclear war. Nothing could be worse for Israel (and possibly its Arab neighbor states as well) than delaying an essential preemption until Iran was already nuclear. Plainly, the best-case scenario for Israel and its regional Arab neighbors would be to neutralize the impending Iranian nuclear threat without having to launch any preemption.

The More Things Change….

Plus, ca change, plus c’est la même chose. “The more things change, the more they remain the same.” Despite continuous efforts to preserve the state and “safety of the People,” Israel remains subject to credible threats of existential harm. The Jewish State, notwithstanding the country’s high levels of military technology and international law’s longstanding presumption of juridical solidarity between all states,[lvii]could sometime face genuine risks of annihilation.[lviii] To prevent such a prospect, Israel could resort to the law-based protections afforded by “anticipatory self-defense.”

As long as Israel’s expression of a permissible preemption had been prompted by imminent attack dangers and was executed in verifiable compliance with the relevant expectations of distinction, proportionality, and military necessity,[lix] the defensive first-strike option could remain lawful. Such lawfulness would not automatically imply corresponding strategic benefits. Always, reliable Israeli judgments of legality and efficacy, though overlapping, would remain analytically distinct.

With an approaching “eleventh hour,” Jerusalem will need to clarify and enhance its nuclear deterrence policy. Special attention ought to be directed toward codifying and maintaining a recognizably survivable and penetration-capable strategic nuclear force. The nuclear options included in this more conspicuous force would need to range along different points along a continuum of military destructiveness. Israel requires not an “all or nothing” nuclear deterrent capacity, but one recognizably subject to various forms of “calibration.”

It will also be important for Israel to continuously enhance its ballistic missile defenses, and convincingly communicate to Tehran that Israeli nuclear forces are (1) usable; and (2) would be used as a complement (not as an alternative) to well-planned BMD interceptions. Among other things, this sort of indispensable communication should include an incremental end to Israel’s “deliberate nuclear ambiguity.”

Israeli Nuclear Deterrence: More Than a Game of Chance

Nuclear deterrence is a “game” that sane national leaders may sometime have to play in the Middle East, but it should always be approached by Israel as a game of strategy, not one of chance. In Jerusalem, this means, among other things, a continuing willingness to respect the full range of doctrinal complexity – both its own military doctrines and those of pertinent enemies – and a corresponding determination to forge ahead with reciprocally complex security policies. Inevitably, to successfully influence the choices that prospectively fearsome adversaries could make vis-à-vis Israel, Jerusalem will need to clarify unambiguously that its conventional and nuclear deterrence are seamlessly intersecting and that Israel stands ready to counter enemy attacks at every decipherable level of possible confrontation.

There remain two final but important points to be made in this examination of Israel, preemption and anticipatory self-defense.

First, whether Israel’s intersecting and overlapping deterrent processes are geared primarily toward conventional or nuclear threats, their success will ultimately depend upon the expected rationality of the nation’s relevant enemies. In those residual cases where such rationality would appear implausible or improbable, Jerusalem could find itself under considerable pressures to strike first preemptively. If Jerusalem’s expected responses were to be judged rational, they might then need to include conclusive and operationally-reliable options for “anticipatory self-defense.” For Israel’s sake, it goes without saying that regional conflict prospects (a) should always be curtailed at the very lowest possible levels of controlled engagement; and that that under no circumstances (b) should Israel find itself having to preempt against an already nuclear adversary.

To prevent such unacceptable but still imaginable circumstances vis-à-vis Iran should represent Jerusalem’s overriding security obligation.[lx]

Second, even the most meticulous plans for preventing a deliberately-inflicted nuclear conflict would not automatically remove the attendant dangers of an inadvertent or accidental nuclear war. While an accidental nuclear war would necessarily be inadvertent, there are determinable forms of inadvertent nuclear war that need not be caused by mechanical, electrical or computer accident. These particular but still-consequential forms of an unintentional nuclear conflict could represent the unexpected result of misjudgment or simple miscalculation, whether created © as a singular error by one or both sides to a particular (two-party) nuclear crisis escalation; or (d) by still unforeseen “synergies”[lxi] arising between singular miscalculations.

Growing Strategic and Legal Uncertainties for Israel

Israel, severely injured by the October 7, 2023 Hamas attacks, is entering into a portentous period of cascading strategic uncertainties. While its national leaders may suggest that security matters are somehow apt to improve, such calculations could merely be wishful. Eventually, Israel would be forced to acknowledge a much less auspicious geopolitical reality.

Even if an American President should succeed in bringing the United States and Iran back into viable and law-oriented negotiations, the cumulative harms of Iranian nuclearization are very unlikely to be halted or reversed. Considered together with continuously inauspicious strategic developments in other parts of the world, this conclusion signifies a basic obligation for Jerusalem to fashion a progressively refined national strategy of nuclear deterrence and nuclear war avoidance.

Louis René Beres was educated at Princeton (Ph.D., 1971) and is the author of twelve major books and several hundred articles dealing with world politics and international law. Professor Beres was an original member of the World Order Models Project at Princeton and Yale during the 1960s. Some of his pertinent writings can be found at The New York Times; The Atlantic; The Bulletin of the Atomic Scientists; The American Political Science Review; The Hudson Review; Yale Global Online (Yale); Harvard National Security Journal (Harvard Law School); JURIST; World Politics (Princeton); International Security (Harvard); The Hill; Horasis (Switzerland); Oxford University Press Yearbook of International Law; the International Journal of Intelligence and Counterintelligence, and Jewish Business News.