The failure of deterrence is not a modern phenomenon; it has accompanied humanity since its earliest days. In the biblical story of the Tree of Knowledge, God warned Adam: "On the day you eat from it, you will surely die." Yet Adam chose to eat the forbidden fruit, demonstrating a fundamental flaw in deterrence: it does not guarantee the prevention of threats. Deterrence relies on both the adversary’s interpretation of the threat and the credibility and determination of the entity issuing it.
At its core, deterrence operates in the psychological and perceptual sphere. Its goal is to convince the enemy that the cost of aggression outweighs its potential benefits. But this is where the challenge lies: how can one accurately assess how an adversary perceives the severity of the consequences or the credibility of the threat? History shows that gauging the impact of deterrence on an enemy is nothing more than an educated guess. States and terrorist organizations may interpret deterrent threats differently from how they were intended—especially over time.
Moreover, deterrence assumes a rational calculation of cost versus benefit. The idea is that if the expected price of aggression is too high, the adversary will refrain from action. However, this assumption does not always hold true. Enemies are often driven by ideological or religious beliefs, which do not conform to materialistic rationality. Political and military leaderships operate within a broad and complex set of considerations, and history is filled with cases where nationalistic, political, or personal motivations outweighed rational calculations.
Additionally, deterrence is not a stable model but rather a temporary state that erodes over time. It is difficult to measure its effectiveness, both for the deterring party and the deterred. Internal political shifts, geopolitical changes, and military developments alter an adversary’s strategic calculus, leading to reassessments of risk. Over time, enemies may test the limits of deterrence, as seen in Hezbollah’s provocations along Israel’s northern border in 2023. Paradoxically, continuous challenges to deterrence can result in the deterring party becoming hesitant, fearing the consequences of using force.
Shlomo Yanai Photo: Yoav DudkevitchFor all these reasons, deterrence cannot serve as the cornerstone of Israel’s national security doctrine. It should be regarded as a desirable byproduct of military, political, and economic strength—but not as a principle on which to rely. Dependence on deterrence fosters rigid thinking, ultimately leading to strategic miscalculations. Instead, Israel must embrace a doctrine of prevention: proactively denying adversaries the capabilities and motivations to act against it in the first place.
