Author: Samaun Fardosy Orthi
International law has to step in and set limits when nations assert self-defence and missiles are fired. Articles 2(4) and 51 in the United Nations Charter clearly define the difference between legal defense and illegal aggression. Israel launched a string of strikes on nuclear and missile targets buried deep within Iran in June 2025. These strikes followed Israel’s bombing of Iran’s consulate in Damascus a few weeks earlier, which then inspired Iran’s more forceful drone and missile strikes. Legal analysis shows both states might have crossed that thin line despite their claims of self-defense.
Article 2(4) of the clear legislation forbids using force against another state. One exception is when Article 51 permits the use of force in self-defense, but only in the case of armed attack and only until the UN Security Council steps in. Under such conditions, all four must be satisfied: an armed attack must take place; a response must be required; it must be proportionate; the state must promptly notify the UN Security Council. As in its historic jurisdictional rulings Nicaragua v. United States and Oil Platforms, the International Court of Justice has confirmed repeatedly that they are not political criteria subject to negotiation.
Iran claimed it was a stand for the Palestinians in Gaza and a reprisal for the Israeli strike on its consulate, using almost three hundred drones and missiles in its April 2024 attack, most of which were intercepted. Though the Iranian attack was usually regarded as an armed attack covered by Article 51, its intention raises legal questions. The self-defense theory does not protect one from acting with force as political retribution or reprisal. Notwithstanding past transgressions, the ICJ has decided time and again that under the Charter reprisals involving force are illegal. Targeting broad-area civilian infrastructure and trying to defend the strike based on events in Gaza, Iran seems to be stretching self-defense outside what the law permits.
Israel’s June 2025 strikes cause a comparable challenge. Iran had begun more missile strikes days earlier, but those strikes stopped by the time Israel responded. Israel targeted deep nuclear facilities as well as missile launch sites, locations far from the actual source of the threat. Under international law, necessity underlines the need for using force only as a last resort when no other peaceful option remains. Based on reports, the need for necessity seems dubious even if a UN-backed truce initiative is already under development.
Proportionality also comes into effect. The ICJ in Oil Platforms advised that force has to be “strictly limited to repelling the armed attack.” Particularly if those sites were not directly connected to the recent missile launches, hitting nuclear infrastructure with dubious military value begs serious questions about whether Israel’s activities were defensive or strategic. The strikes go from defense to aggression if their targets were to disable Iran’s future capacity or tip the regional balance of power.
The UN General Assembly defines aggression, a concept further reinforced by the Rome Statute of the International Criminal Court, as the employment of armed force by one state against another in violation of the Charter. States act hostilely even claiming self-defense when their actions fall short of the strict standards for justification. In this regard, Israel’s strike belongs in this category if its actions were neither commensurate with the real damage done nor necessary to reduce a future threat.
Finally, we cannot ignore the procedural requirement of reporting to the Security Council. Iran, after its April attack, submitted a formal Article 51 notification. Israel, however, has not publicly done the same after its June operation. While failure to report does not automatically make a use of force illegal, the ICJ has recognized it as an important test of a state’s sincerity. The absence of such a report weakens Israel’s legal claim and suggests that it may have acted without full regard for international accountability.
In the end, both Iran and Israel claimed the right of self-defense, but both appear to have ignored the rules that define its limits. The line between lawful defense and aggression may be narrow—but it exists for good reason.
The writer is law student at American International University-Bangladesh (AIUB).
