Preventive War: Its Disappearance from Israel’s Security Toolbox and the Need for Its Return

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By Brig. Gen. (res.) Dr. Meir FinkelApril 21, 2024

IDF Spokesperson

BESA Center Perspectives Paper No. 2,270, April 21, 2024

EXECUTIVE SUMMARY: Preventive war/the preemptive strike, defined as the identification of a major threat developing among one’s enemies and the taking of action to remove that threat before it materializes, was once central to Israel’s security concept. Since the rise of Hamas to power in Gaza and the Second Lebanon War against Hezbollah, however, the IDF has abandoned this practice. Instead, strategies were developed to keep escalation below the threshold of war – the “Campaign Between the Wars” in the north and repeated limited operations in Gaza. Notwithstanding these efforts, both Hamas and Hezbollah subsequently evolved, over the course of almost two decades, into terrorist armies that are a significant threat to Israel. Two recent cases illustrate this trend: Israel’s response to the development of Hamas’s offensive capability, with an emphasis on tunnels, starting in 2015; and Hezbollah’s conversion of rockets into precision-guided rockets starting in 2018. In both cases the option of a preventive war was raised but rejected. In direct response to lessons learned from the Iron Swords War, I propose that the preventive war/preemptive strike be restored to Israel’s strategic toolbox. The external and internal legitimacy for doing so stems from the fact that Israel has returned to the era of “wars of no choice.”

Over the course of the still-continuing Iron Swords War, members of both the military and the general public have claimed that they identified the severity of the Hamas threat as long ago as the middle of the last decade and demanded in vain that the government initiate a preventive war against it. Similar demands were made, shortly after the outbreak of the current war, to launch a preemptive attack against Hezbollah before it too could attack Israel’s border communities. Such an attack has not yet occurred.

In addressing this matter, this article differentiates between two historical periods:

First, from the establishment of the state until the 1980s. During this time, the idea of preventive war was a central component of the Israeli security concept against the surrounding hostile states. It applied both before the enemy completed a force build-up that could have potentially changed the military equilibrium against Israel (1956) and when an actual threat became imminent and intolerable (the preemptive attack carried out in 1967 and considered as a possibility in 1973). If applying the nuclear context, this period stretches to the first decade of the 21st century (the bombing of the Iraqi nuclear facility in 1981 and that of Syria in 2007).

Second, the period after the Second Lebanon War in 2006 and continuing to the present. During this period, preemptive war/the preemptive strike gradually disappeared from Israel’s security policy dialogue while facing the development of two main enemies, Hamas and Hezbollah.

Against Hezbollah, a substitute strategy was developed in the form of the “Campaign Between the Wars.” This strategy aimed to prevent the enemy’s force build-up by conducting repeated small-scale attacks to destroy specific assets that were considered especially threatening to Israel. The strategy did not prevent Hezbollah’s build-up because it had a ceiling: “below the threshold of war.”

Against Hamas, a similar though much less intense campaign began as an improvisation during Operation Protective Edge, which had begun for other reasons but which became focused on destroying Hamas’s offensive tunnel system. This was followed over the coming years by occasional attacks on newly dug offensive tunnels. However, no similar campaign was waged against Hamas’s other force build-up programs, such as the Nukhba units.

A central argument in recent decades against preventive wars of any kind was the difficulty of obtaining international legitimacy for “strong” Israel taking action against “weak” Hamas or Hezbollah, as well as the need to build internal legitimacy for the casualties who would be lost in such actions. The argument was that there were ostensibly “cheaper” alternatives, such as limited operations in Gaza or the “Campaign Between the Wars” in Lebanon and Syria.

I propose that these assumptions are no longer valid. Israel must return preventive war to the center of political and military thinking, with an emphasis on Hezbollah and the other Iranian proxy militias.

Preventive war, the preemptive attack and the preemptive strike: Israeli definitions and history

In his book on battlefield decision in Israel’s wars, Avi Kober discusses three categories of preventive warfare action:

A Preventive War is a war initiated by the party that perceives a potential threat, neither immediate nor certain, that could detrimentally change the relationship of military power between it and its enemies. Initiating such a war is problematic because of the difficulty of assessing future abilities and intentions of the possible enemy and the difficulty of convincing both the local and international publics that such a war would be a justifiable act of self-defense rather than an act of aggression. It is therefore a rare phenomenon. The main example from Israel’s wars is the Sinai War in 1956, which was intended to halt the growing threat from Egypt (though there were other reasons involved as well).

A Preemptive Attack is initiated by the party that perceives a highly probable imminent threat in the increasing deployment of enemy forces near the common border. The preemptive attack is meant to disrupt the enemy’s offensive preparations by attacking him before they are completed. An Israeli example is the preemptive attack on Egypt in 1967. This category, also called “first strike,” is one of the basic principles of Israel’s air force doctrine for achieving air superiority, such as that achieved in 1967, planned but deferred for political reasons in 1973, and achieved in 1982.

A Preventive Strike is a small-scale military operation, well below the threshold of war, that is conducted to delay the enemy’s force build-up or a specific evolving threat capability. An Israeli example is the bombing of the Iraqi nuclear reactor in 1981, which was intended to disrupt and delay the development of nuclear weapons by Iraq.

This article focuses on preventive operations – a war or a strike – designed to neutralize the Hezbollah threat before it has fully matured. It does not address the issue of a preventive strike against the Iranian nuclear program.

From the Ben-Gurion Doctrine (1956) through the Begin Doctrine (1981) and from Olmert (2007) to Netanyahu vis-à-vis Iran and Hezbollah (prevention of force build-up below the threshold of war)

It appears that the main cause for the decline over the years of the concepts of preventive war, the preemptive attack and the preventive strike was a sense that the relevant threats had declined to such a degree that they could be dealt without incurring the problems associated with preemptive actions. The idea was that such attacks could only be justified by an “existential threat” like a nuclear bomb. Such an event was the preventive strike against the Syrian nuclear reactor in Deir ez-Zor in 2007 ordered by Prime Minister Ehud Olmert despite the risk that the action would lead to a full-scale war with Syria. (The Iranian nuclear threat has put this idea back on the Israeli agenda, but as noted, I will not elaborate here on the issue of preventive war/preventive strike to neutralize this threat.)

The IDF’s conceptual documents discussed below express the core of the IDF’s operational focus during each period, and also refer to the years since the Second Lebanon War (2006) with a brief discussion of two case studies from the past decade.

In the IDF strategy document of 2002, which addresses wars between states, the main concern is protecting Israel’s borders against an enemy invasion. Three terms are used extensively throughout the document. The first is a “Preemptive Attack,” which the political echelon would instruct should be carried out in the following situations: “The lack of an operational military ability to prepare an effective defense due to the lack of sufficient depth; an assessment that if we allow the enemy to determine the timing, we will risk difficulties that may endanger [Israel’s] existence; an unprecedented strengthening of enemy capabilities so that only the use of force on our part will neutralize the danger it poses;” or that “the prosecution of war in [Israeli] territory [would] entail unbearable damage and losses for us, [rendering] it necessary for us to ‘transfer the war into the enemy’s territory’. For these and other reasons, in conducting a Preemptive Attack, we are not the aggressor, but act only in self-defense – while the real aggressor is the enemy, even though on the operational or tactical level, he is the defender.”

The second term, “Preemptive Strike,” was presented as a focused military action to remove a specific developing threat. The third term used in the concept paper was “Parallel Strike” – a situation in which the enemy is about to employ his capability but is prevented from doing so because the IDF responds just in time by striking that capability. A detailed footnote states that Chief of Staff Shaul Mofaz sees a preemptive strike as a fundamental principle in the IDF’s concept of operations.

In the 2006 IDF operational concept document by Chief of Staff Moshe Ya’alon and accepted by his successor Dan Halutz, it was claimed that a surprise offensive is an element of the past concept of deterrence / early-warning / battlefield decision. The new concept was written in the context of the operations against Palestinian terrorist attacks in Judea and Samaria and the rise of the Iranian nuclear threat. The idea of preventive war was discussed under a new designation called “preliminary moves.” The document stated that “a preemptive strike is intended to thwart the formation of a potentially significant threat, while considering issues of legitimacy and international law before deciding on a preliminary military move; i.e.: the ability to justify the move retroactively within the framework of the right of self-defense. For this purpose, the IDF needs capabilities aimed at thwarting or disrupting an arc/spectrum of threats and to achieve legitimacy by presenting ‘conclusive evidence’ and ‘incriminating evidence’ of the threat as a condition for the preventive actions.” These expressions indicate that the threat was no longer identified as a military invasion across the border. Elsewhere in the document, concerning the prospect of an “all-out war” with a hostile army, it says that a “preemptive strike” exists as part of the IDF’s operating concept and aims to provide a relative advantage against an enemy who is clearly prepared for war, according to its deployment and operational concept.

In the IDF’s 2015 strategy document by Chief of Staff Gadi Eisenkot, which focused on Hezbollah and Hamas, the idea of the “Campaign Between the Wars,” which presented a pattern of preventive action that remained below the threshold of war, was presented publicly for the first time:

“The logic of the use of force in the ‘Campaign Between the Wars’ is to preserve and enhance the achievements of a previous campaign by attacking a series of primary or secondary objectives designed to distance the [future] war:

Weaken the hostile actors.

Reduce the enemy’s force build-up.

Create optimal conditions for victory in a future war.”

The 2015 document still contains references to Preventive War operations. In a paragraph dealing with “developing capabilities vis-à-vis countries without a common border” (i.e., Iran), it was noted that the building of the force would be based, inter alia, on “intelligence providing warning early enough to conduct a preemptive strike.” The idea of the “surprise attack” was also dealt with by Eisenkot; the document says the IDF’s fire capability had to ” be able to launch a massive fire-strike within a few hours.” While these ideas were still present in IDF thinking at the time, they were on the margins.

It was reported that in Prime Minister Benjamin Netanyahu’s “2030 Security Concept,” which he wrote in 2018 but which was never fully published, he wrote:

“Between the wars we will act to harm the processes of building the enemy’s force below the threshold of war. We will not allow our enemies to cross an irreversible [originally “intolerable”] threshold, or, given a warning of an impending strategic surprise,… [“we will conduct a preemptive attack” – erased].

Source: Haaretz

Two case studies from recent years illustrate the decline in the centrality of the idea of a preventive war: combating Hamas’s offensive capability, especially the tunnels; and combating Hezbollah’s conversion of rockets into precision-guided rockets (sometimes wrongly referred to as missiles).

Preventive action against Hamas tunnels

Operation Protective Edge demonstrated to anyone who was not previously aware that there existed the potential for a Hamas attack through offensive tunnels crossing into Israeli territory from Gaza. The IDF announced that during the campaign it had destroyed hit 30 tunnels, and indicated that Hamas was prepared to conduct a broad and decentralized operation that was not yet implemented when the Israeli operation began in response to escalated rocket fire from Gaza.

After the operation, the IDF continued to operate against the offensive tunnels, but Hamas did not abandon the project of constructing and equipping them. This situation, and the conduct of Hamas in general, led Israel’s defense minister at the time, Avigdor Lieberman, to propose in December 2016 that Israel embark on a “preventive war” (though in a document he sent to Prime Minister Netanyahu, he used the phrase “surprise strike/preemptive attack”). Lieberman wrote that “Hamas intends to transfer the war to the territory of Israel in the next conflict, streaming significant and well-trained forces (e.g., Nukhba forces) into Israeli territory while occupying an Israeli settlement (and possibly several settlements) in the Gaza Envelope area, and taking hostages, which, beyond the physical harm to the people themselves, will lead to severe damage to the consciousness and morale of the citizens of Israel.”

Lieberman claimed that a surprise strike/preemptive attack was necessary and that delaying the decision to conduct such a strike on Gaza during the summer of 2017 would be a mistake with extensive negative consequences. He said those consequences could, in some ways, be more damaging than the aftermath of the Yom Kippur War in terms of repercussions for the Israeli civilian rear, the state of mind of the Israeli citizenry, and the image and standing of the State of Israel in the region.

Netanyahu did not accept Lieberman’s position, which, according to Lieberman, ultimately led to his resignation as minister of defense.

The head of the INSS, Maj. Gen. (res.) Amos Yadlin, wrote in February 2016, in connection with the Hamas tunnels, that the concept of preventive war/preemptive attack should be applied to this threat. After discussing various alternatives, he concluded, “In the current basket of considerations vis-a-vis the Gaza Strip, the optimal solution for Israel is to find a technological solution against the threat of the offensive tunnels, which will make it possible to postpone the inevitable confrontation with Hamas and be in a better position when it breaks out. However, the immaturity of such a solution creates a dilemma at the current point in time as to the desired course of action. Israel must determine that if it knows there are tunnels crossing the border into Israel, and that Hamas is preparing to use them, it will be required to conduct a preemptive strike. If, as a result of such an attack, there is an escalation to full-scale war, it must be short and powerful, based on a clear strategic purpose, and with a horizon for a significant change in the balance of power and dynamics between the parties – unlike all previous rounds.”

For a variety of reasons, primarily the desire to preserve the quiet or return to it quickly after a short confrontation and the belief that Hamas was deterred from a large-scale confrontation, the idea of a preventive war was ruled out at that time.

Preemptive action against Hezbollah’s precise fire capability

The development of Hezbollah’s precision-guided rocket threat brought the matter of a preventive war to both military and public debate. In 2018, former minister Gideon Sa’ar claimed that:

“Hezbollah has established factories to convert long-range heavy rockets into missiles that can hit anywhere in the State of Israel […] We need to ask ourselves whether we want to wait and meet with Hezbollah when it has a quality strike capability on the civilian and military infrastructure of the State of Israel […] Israel must act today with a preemptive strike on those precision missile factories that are being built in Lebanon.”

In February 2021, it was reported that “the army maintains that Hezbollah holds a few dozen precision missiles, and therefore military intelligence still does not recommend a preemptive attack against Hezbollah against this strategic capability, as long as other arrays against Hezbollah’s precision project are still being employed.” The head of the Military Intelligence Directorate, Maj. Gen. Tamir Heiman, said, “We work and deal regularly with the threat of precision missiles and provide a solution in a variety of ways, openly and covertly.” Brig. Gen. Eran Niv, head of the Shiloah Division in the Planning Directorate, said at the same time that “if Hezbollah passes the threshold of quantity or quality of precision weapons, we will be required to act against it. This is a heavy decision, but we cannot escape it.” INSS Institute head Major General (res.) Amos Yadlin said, “If Hezbollah accelerates its buildup, Israel will be required to consider a preemptive strike in order to deny its ability. Other parties believe that Israel must not initiate such a move that will certainly lead to war.”

It should be noted that the logic of Operation Northern Shield to neutralize Hezbollah’s offensive tunnels in 2018 was a “preemptive strike” to neutralize Hezbollah’s ability to use them in a future war. It was a kind of “Campaign Between the Wars” operation, since the methods Israel used ensured that the operation would not escalate into a war.

In 2023, Evyatar Matanya and Menachem Bachrach proposed that preventive actions against nuclear weapons be defined and that the “Campaign Between the Wars” be placed under the heading “Strategic Prevention” – an action aimed at eliminating a strategic threat before or during its creation, so the enemy would have to rebuild the capability from scratch. They identified this as the fifth principle of Israel’s national security concept (deterrence / early-warning / defense / battlefield decision) to compensate for the weakening of Israel’s ability to achieve battlefield decisions. Their proposal distinguished between a “strategic denial,” which is directed at the building of power; and a preemptive strike, “whose essence is not a process of impeding the building of capabilities, but rather an attack on the ability to use that capability just before its implementation.” This proposal justified the “Campaign Between the Wars” against Hezbollah’s force build-up as a cost versus benefit computation, but did not suggest initiating a war in Lebanon.

To summarize this period, it can be said that the use of preventive war to remove an evolving threat was replaced by the “Campaign Between the Wars,” which was intended to degrade the enemy’s