Has the concept of deterrence, long a cornerstone of Israel’s defense doctrine, been rendered largely irrelevant? Do the lessons of the war so far – the Hamas assault on October 7, 2023; Hezbollah’s decision, a day later, to join the fray with mid-intensity attacks on Israeli targets; the Houthi campaign to disrupt shipping in the Red Sea and launch long-range attacks; and two Iranian missile barrages against Israel – prove, as some scholars suggest, that Israel’s well-known military strength is no longer sufficient to deter its enemies?
It may well be true that the traditional understanding of deterrence – along with other elements of the Ben-Gurion-era defense doctrine, crafted seventy years ago to address the threat from regular Arab armies – should have been revised to deal with current circumstances, the changing nature of war and new types of adversaries. It is also important to bear in mind that deterrence is a slippery concept: one that is in essence, a psychological state, subject to erosion over time, rather than a concrete reality.
And yet, it would be a mistake to dismiss the concept of deterrence or belittle its enduring importance – even if other elements of the doctrinal equation, specifically defensive capabilities, should be moved up the ladder of priorities to respond to situations which arise when deterrence fails. As it happens, Iran did take into account deterrent messages sent by both Israel and America– even as it ultimately chose to attack and risk retaliation. Similarly, deterrence influenced Hezbollah’s decision to opt for a static war of attrition, rather than escalating to full scale conflict –a stance it maintained until September 2024.
Rather than dismissing deterrence, it would be wiser to adjust the concept to new realities, and leverage for this purpose Israel’s proven ability and willingness, as demonstrated in Lebanon, to use force effectively and in a determined fashion. Vital as it is, force buildup is not sufficient to create deterrence: it must be coupled with political decisiveness and social cohesion.
Has Deterrence Become Irrelevant?
Well before the Hamas onslaught on October 7, 2023, there were scholarly warnings that the key concepts of Israel’s defense doctrine – deterrence, early warning, and decisive outcome (often attributed to Ben Gurion, although he did not use this “trinity” in his presentation to the Cabinet in 1953) – have lost their meaning in today’s world. Most significantly, “deterrence” as traditionally understood no longer against terror groups of a hybrid nature, with some attributes of a state, operating at times in large formations, yet retaining their insurgent characteristics and driven by a deeply religious and fanatical revolutionary agenda, and willing to accept massive sacrifices.
In essence, deterrence is an aspect of an adversary’s leadership thinks; as such it always involves far that calculations of relative military strengths. Cost/ benefit perceptions evolve over time, and without intelligence access to the innermost circles of decision-making – and even then, as Israel found out in 1973 that too doesn’t always suffice –it is not possible to realize in advance that deterrence has in fact eroded and evaporated, until after an attack. This was the case when Hamas attacked in May 2021 and even more so in October 2023.
Since deterrence is ultimately a psychological construct, an acute question arises: can it be of significance in the defense doctrine of a country – like Israel – facing a prolonged state of conflict? The problematic nature of the concept of deterrence was highlighted recently in another part of the world: Ukraine’s invasion and conquest of sovereign Russian territory in the Kursk region exposed the uncertain nature of a related notion: “red lines.” For Russia, in theory, its deterrent posture was supposed to trigger a massive response, possibly even the use of nuclear weapons, when areas within Russian itself were captured). This demonstrates once again that a complex relationship exists between the levels of determination – that of the deterring party and that of the deterred one. In turn, this complexity adds to the challenge of early warning. Given the fragility of deterrence, a whole system of “telltale signs” needs to be developed to know that it has indeed fallen apart, and the enemy is about to take the initiative.
In light of these changes, there are those who advocate a far-reaching re-definition of Israel’s defense doctrine, emphasizing a greater reliance on permanent defensive capabilities and measures. Had such effective elements been in place in October 2023 (or October 1973) they could have mitigated the blow – even in the event of a failure of both deterrence and early warning. Given the strain the war has placed on Israel’s resources, the ability not only to halt an attacker but to defeat them decisively and impose a heavy cost becomes essential. This requires enhanced ground forces, not only for deterrence, but to be able to take effective action. In the hierarchy of defensive concepts, reliance upon deterrence should be demoted in favor of a more robust military capacity to respond to any contingency. This is the lesson of the October tragedies.
Still, deterrence must not be left for dead in the battlefield. For Israel seeks to survive and thrive in the region, given that it cannot bend Arab political realities to its will, it must retain the capacity to deter potential attackers. It must be made clear to any would-be adversary that the cost of aggression would far outweigh any potential gain.
Enhanced defensive capabilities that can thwart an attack, along with a strong maneuvering force that can exact significant costs – in addition to retaining air superiority – would have this effect, if backed by a clear message regarding Israel’s proven determination to act. If the enemy is convinced that an attack would fail – whether due to effective defense and/or preventive measures and preemption – and that the punishment it would suffer would be intolerable, the level of danger would decrease consequently.
The Various Levels of Deterrence
For Israel, as for any country compelled to maintain deterrence (unlike many modern European nations, which from the 1940s until recently comfortably outsourced this mission to the Americans…), what the enemy knows or fears about its military power and its willingness to use it, can produce varying levels of deterrence:
- At the level of strategy or even grand strategy, an adversary may conclude that there is no prospect of destroying Israel by force, and hence even choose the option of a diplomatic solution that accepts its existence as a fact, even if it still doubts the legitimacy of its creation. The presence, in the mind of Arab leaders, of Israel’s undeclared deterrent – the nuclear capability attributed to it – as well as the long-term implications of U.S. backing, played a pivotal role in bringing Egypt to the Peace Treaty of 1979, and since 1974 has dissuaded Syria from taking any military initiative against Israel.
- Even for those who remain adversarial – as is the case with Syria – the decision to act, in particular the timing of any military offensive, may well be influenced by the balance of power. The well-known capabilities of the IDF, coupled with its preparedness, readiness and willingness to act, can generate deterrence at the operational level: not a strategic realignment, as described above, but a more modest decision that the timing is not right for an attack. For example, for 17 years, from the war of 2006 until 8 October 2023, – an equation of (mutual) deterrence existed between Israel and Hezbollah in Lebanon, and there were almost no direct hostilities along the border. This stands in contrast to the airspace of Syria, where Israel has been conducting its “Campaign Between the Wars” against Hezbollah’s supply lines.
- At the tactical level, even during active wartime, there are capabilities that the adversary is deterred from using, fearing fierce retaliation and the loss of its assets. Hence the limited nature of Sadat’s war in 1973; and even Hassan Nasrallah’s attempt – in the present war – to maintain certain “rules of the game” with Israel, and thus conduct a static war of attrition rather than an all-out offensive. In this respect, deterrence “works”: it may not prevent war, but it does influence its conduct. Only in the case of Yahya Sinwar’s gamble on total war (for which he ultimately paid with his life, alongside tens of thousands of his men) can it be said that deterrence – in terms of the projected price that may be exacted – did not avert the ideologically driven imperative for action.
Each of these levels requires specific deterrent elements effective to it. Hence Israel’s decision to respond in a much more extensive manner to the second Iranian missile barrage than to the first – while leaving room for further escalation should there be a third assault. In all cases, it should be borne in mind that deterrence is inherently unstable, tends to become a “wasting asset”, and needs to be sustained by demonstrations of power and the willingness to use it. Effective defense and prevention capabilities are also part of the deterrent equation, and had they been in place on October 7, 2023, the outcome might have been very different.
No Deterrence Without the Determined Will to Act
As the post-1945 global dispensation falls apart – and while some in the West, almost pathetically, try to put the liberal order together again – Israel’s ability to survive has come to rest on its own national power as well as on local alliances. Two key requirements stand out, in addition to (not as a substitute for) the impact of military power:
- The core of the concept of deterrence – as U.S. presidents understood during the Cold War era – is above all a question of the will and determination to act. This is not simply a matter of formal “red lines” but of leadership, authority, and largely of domestic support. It is difficult to avoid the thought that the evident cracks in Israel’s national cohesion during the first nine months of 2023 (without assigning blame) contributed to an erosion of deterrence. They fed the “spider’s web” imagery used by Hasan Nasrallah – for which he, too, ultimately paid with his life – and forced Israel to react in a far-reaching manner in order to restore its deterrent image.
- Of a lesser, but not insignificant, importance is the question of legitimacy for the types of action that can establish deterrence. Organizations motivated by a totalitarian religious-revolutionary creed, such as Hamas and Hezbollah, deliberately seek to draw Israel into actions that harm their own civilians. The cost of these actions to Israel’s standing in the U.S. and Europe can outweigh the benefits. Hence the vital need, in the context of enhancing deterrence, for coherent strategies aimed at educating elites and publics in the West as to the reasons behind Israel’s choice of military means. At the same time, it is also necessary – for strategic, not just “queasy” moral reasons – to try as much as possible, as the IDF indeed does, to distinguish specific enemy targets from non-combatants. Those who adamantly advocate wholesale destruction as a deterrent should bear in mind the tension between exacting a price from the enemy potentially paying an even higher cost in terms of Israel’s legitimacy in a Western culture sensitive to civilian casualties.
The blows dealt to Hezbollah since mid-September 2024 have restored Israel’s deterrent posture: One clear indication is that in general, Hezbollah troops on the ground frequently withdrew and sought to avoid engaging in organized battles, though there have been some painful exceptions. Still, the ultimate key to restoring the equation lies in several critical factors: forcing Iran to pay the full price for its active intervention; the ability to demonstrate that Israel has lost neither its determination nor its capacity to take well thought out decisions; and the resilience and coherence of the Israeli public at large under fire. Rocket fire and drone attacks persist, at times taking a painful toll: but what matters is their impact on the willingness to pursue the war to a successful outcome.
In summary, deterrence with all that it requires and implies will continue – despite its problematic nature – to constitute a key pillar of Israel’s defense doctrine and indeed of its grand strategy. This will require attention to both resilience and legitimacy. All this should not diminish, however, the urge to enhance other pillars, including a re-defined mission of border defense.
JISS Policy Papers are published through the generosity of the Greg Rosshandler Family.
Photo: IMAGO / ZUMA Press Wire / Israel Mod
