Filenews 27 June 2025
Jill Goldenziel
Even if the U.S. and Israel have completely destroyed Iran's nuclear program, the legal and strategic implications are now beginning. Both Israeli strikes and U.S. bombings of Iran's nuclear facilities face accusations of violations. Legal arguments within the U.S. bring to the fore complex and important issues of executive power. Under international law, however, Israel's attack on Iran was legal. However, the debate that has developed over the legitimacy of Israel's aggression reveals gaps in international law that may affect future wars.
When did the Israel-Iran war start?
To determine the legitimacy of Israel's actions, we must first ask ourselves whether Iran and Israel were in armed conflict before Israel's June 13 strikes. The Law of War applies only in armed conflict. However, international law does not clearly define how an armed conflict begins and ends. Rarely do states declare war on each other and then sign an unbroken ceasefire.
Israel and Iran have maintained a hostile relationship for decades that is interrupted at times by Tehran's direct involvement and proxies attacks against Israel. Iran began supporting Hezbollah in 1982 after Israel's invasion of Lebanon. Hezbollah has repeatedly attacked Israel and has been involved in terrorist attacks against Jewish and Israeli sites around the world. Hezbollah and the Houthi rebels in Yemen are seen as Iran's proxies in the Middle East, and there is strong evidence for Iran's support for Hamas. Legally, for an organization to be considered proxy for Iran, Tehran would have to exercise control by giving direct orders. Funding and supplying weapons to a group does not make it a proxy of a state. From time to time, these groups may act on their own initiative against Israel. However, for decades these organizations have repeatedly acted in coordination with Iran – in fact, they would not have carried out many of their actions without Iran's support. The combined moves of these groups reinforce the argument that Israel is in an armed conflict with Iran long before June 13.
Israel and Iran have been exchanging field attacks and cyberattacks for decades, which have intensified in recent years. Iran launched drones and missiles at Israel in 2018. Israel responded with airstrikes and drone strikes against Iranian positions in Syria and Iraq and eventually on Iranian territory in 2023 and 2024. "An eye for an eye" attacks on ships occurred in the 2020s. In 2024, Israel bombed the Iranian consulate in Damascus, killing a general of the Quds force of the Iranian Revolutionary Guard. Iran responded by launching 300 missiles and drones against Israel. Israel subsequently struck an air defense radar and a ballistic missile facility near Isfahan.
Given these direct and indirect attacks for decades, it can be assumed that Israel and Iran were in an armed conflict. However, the failure of international law to define when armed conflict begins reveals a crucial gap. Many states are involved in conflicts that are repeated. The ambiguity of international law on this issue leaves states exposed to accusations of violations.
Israel's strikes were legitimate due to direct threat
Even if there was no armed conflict between Israel and Iran, Israel's strikes were justified as an act of self-defense. Article 51 of the United Nations Charter says that states have the right to self-defense. According to customary international law, a state may engage in preventive self-defense when an armed attack is imminent. However, the term "imminent" (for an attack) is not defined in International Law. Distinguished experts argue that states can use preemptive force when (1) evidence indicates that the aggressor is committed to an armed attack, and (2) delaying the response would impede the ability to defend effectively. Proactive self-defense is permissible "when the attack is imminent and there are no reasonable alternatives."
To assess the legitimacy of Israel's strikes, we must consider whether an armed attack by Iran was imminent, whether Iran was committed to an armed attack, and whether delaying a response would impede Israel's ability to effectively defend itself. Intelligence assessments of Iran's nuclear program are disputed. U.S. Director of National Intelligence Tulsi Gabbard testified to Congress that Iran was not trying to build a nuclear weapon. However, the International Atomic Energy Agency reported on May 31 that Iran had violated its obligations under the Treaty on the Non-Proliferation of Nuclear Weapons by citing sites, materials and activities that had not been declared by Tehran and that could be used to build nuclear weapons. The IAEA Director-General said in April that Iran was months away from building a nuclear weapon. A study estimated that Iran was just a week away from its target.
Iran appears to have committed itself to an armed attack. Iran's leaders have called for Israel's complete destruction for decades. The negotiations had failed. According to Israel's view of the facts and circumstances, it could reasonably conclude that it had only one week to defend itself from the threat of disaster – and that the law would justify a pre-emptive strike. In a letter to the Security Council on June 17, Israel said its strikes were a measure of last resort to deter imminent Iranian attacks and that it was the "last window of opportunity" to ensure its survival.
The future of wars
Under international law, Israel's strike was legal. However, it raises important questions about the future of international law – and the future of wars. As I often say to my students, we don't have a law for the world we live in – but the law still matters. International law does not tell us when the armed conflict begins and ends. The model of "immediate" self-defense requires a rethinking in the age of cyberattacks and weapons that threaten the survival of a state. The law of war exists to make war more just and less brutal, and to ensure a peace on better terms when the whirlwind of war has passed. It has served this purpose since the end of World War II, when all modern states agreed to say "Never again" to the atrocities of that war. In order for the law to continue to serve the same purpose, the international community will have to agree on its content, but also on the definition of war. Without clarity as to what the legal framework provides for and requires, we risk living in a situation of constant war, where no rules apply.
