The post-World War II international legal order, institutionalized through the United Nations Charter, established a comprehensive framework aimed at regulating and restricting the unilateral use of force by States. At the heart of this framework lies Article 2(4), which unequivocally prohibits the threat or use of force against the territorial integrity or political independence of any State. This prohibition is reinforced by a narrowly circumscribed exception found in Article 51, which permits the use of force solely in the case of self-defence "if an armed attack occurs." This clear textual formulation enshrines the principle that the right of self-defence arises only in response to an actual armed attack, thereby rejecting broader or speculative justifications for the use of force.



Despite this restrictive construction, recent decades have witnessed a growing number of attempts by certain States and scholars - predominantly from Western jurisdictions - to reinterpret or expand the scope of Article 51. These efforts aim to legitimize the use of force against perceived imminent threats, even in the absence of an actual attack, under what is variously described as anticipatory, pre-emptive, or preventive self-defence. This revival of pre-Charter doctrines represents a significant departure from the Charter’s original intent and poses serious risks to the stability of the international legal order.



This article critically engages with these developments, focusing on how legal, doctrinal, and political strategies are employed to erode the threshold for lawful self-defence. Specifically, it observes that certain States have relied on increasingly permissive and indeterminate terminology to normalize pre-emptive uses of force. Central to this trend is the selective and often ahistorical invocation of the Caroline incident - an 1837 exchange between the United States and Britain often cited as the foundation for customary self-defence principles. While the Caroline criteria emphasized the necessity of self-defence in situations where the need is “instant, overwhelming, and leaving no choice of means, and no moment for deliberation,” modern reinterpretations tend to obscure or dilute these standards, often deploying them to justify force against threats that are neither immediate nor overwhelming.



Moreover, this article highlights the emergence of a self-referential cycle of legal reasoning in which a limited set of Western-authored academic works, policy statements, and military manuals repeatedly cite one another. This recursive citation practice contributes to what may be termed a “doctrinal snowball effect,” whereby repetition is mistaken for legal consensus. The cumulative impact of such scholarship risks creating the illusion of an emerging customary norm that permits anticipatory or preventive use of force, despite the absence of widespread and consistent State practice or opinio juris to support such a shift.



To ground its analysis in a concrete and timely case study, the article examines Israel’s June 2025 airstrikes against Iranian targets, which were publicly justified as acts of pre-emptive self-defence. According to Israeli officials, the strikes were necessary to neutralize Iran’s advancing nuclear capabilities, which were portrayed as posing an existential threat. However, the legal justification advanced relied heavily on projected future threats rather than any specific or imminent armed attack.



Applying the jus ad bellum framework as codified in the UN Charter and interpreted by the International Court of Justice (ICJ), this article contends that Israel’s rationale fails to satisfy the core legal requirements for lawful self-defence. The ICJ has consistently affirmed that self-defence under Article 51 is triggered only by an actual armed attack. Furthermore, the requirements of necessity and proportionality are not merely rhetorical thresholds but substantive legal constraints. A threat that is hypothetical, remote, or speculative cannot qualify as “necessary” in the legal sense, nor can military action taken on such a basis be considered proportionate.



This article also critically examines the possible invocation of the Caroline doctrine by Israel to justify its actions. It finds that, even under the more flexible customary law framework predating the UN Charter, the threshold for lawful anticipatory self-defence remains exceptionally high. The Caroline standards require a demonstrable imminence of threat, a condition not met by Israel’s 2025 strikes. Instead, the justifications offered reflect a form of preventive self-defence - aimed at neutralizing potential future threats rather than responding to an immediate danger - which lies outside the boundaries of established international law.



Through a detailed doctrinal analysis supported by ICJ jurisprudence, State practice, UN Security Council deliberations, and prevailing opinio juris, the article argues that recognizing a unilateral right to pre-emptive self-defence would fundamentally undermine the jus cogens character of Article 2(4). It would weaken the collective security architecture envisioned by the UN Charter, encourage opportunistic uses of force under the guise of pre-emption, and erode confidence in the rule-based international system.



Accordingly, the article concludes that Israel’s June 2025 airstrikes on Iran constituted a violation of international law. The threats invoked were not imminent in the legal sense, nor was the use of force necessary or proportionate. The purported right of pre-emptive self-defence advanced in this case lacks support in both treaty law and customary international law. Ultimately, the article reaffirms that, in the absence of a manifest armed attack or Security Council authorization, unilateral uses of force cannot be reconciled with the Charter’s foundational principles. The doctrine of pre-emptive self-defence remains incompatible with the existing jus ad bellum regime and poses a serious challenge to the integrity and stability of the international legal order.