Israel’s Attack on Iran’s Nuclear Weapons Program is Fully Justified Under International Law

Several of these commentators have based their contention that Israel’s attack is illegal on their opinion that Israel was not responding to an “imminent” nuclear attack by Iran. But this argument overlooks a critical legal principle: When two countries are already in a state of armed conflict—in colloquial terms a war—there is no requirement to wait for “the next attack” to be imminent.

Israel’s attack on Iran’s nuclear weapons program, including its ballistic missile capabilities, was legal because Iran and Israel were already engaged in an ongoing international armed conflict. Furthermore, even assuming for argument’s sake that this was not the case, the imminence test was met by the facts in place on June 12, fully justifying Israel’s invocation of the international legal right for a state to defend itself against an imminent unlawful armed attack.

The armed conflict between Iran and Israel has been ongoing since at least April 13-14, 2024, when Iran fired over 300 drones and missiles at Israel and, in the view of some experts, even prior to this date as the result of attacks against Israel by Iran’s main proxy, Hezbollah. Then, on October 1, 2024, Iran launched at Israel over 180 missiles, reportedly the largest ballistic missile attack in history. In late May 2025, Major General Abdolrahim Mousavi, commander-in-chief of Iran’s army, threatened another similar missile attack against Israel to “collect on what they already owe us.”

While an armed conflict continues, there is no requirement to justify every attack against the enemy through the pre-war imminence test. With Iran already engaged in ongoing conflict with Israel, international law did not require Israel to wait to take military action against these vital enemy assets until just before Iran either launched a nuclear missile against Israel or otherwise fired its proverbial next shot. Instead, it was legal, as well as logical, that Israel attack the enemy’s most dangerous weapon system—in this case, Iran’s nuclear weapons program.

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LTC Geoffrey Corn, USA (ret.), a Texas Tech University law professor and JINSA distinguished fellow, previously served as the U.S. Army’s senior law of war expert. Orde Kittrie, an Arizona State University law professor and senior fellow at the Foundation for Defense of Democracies, previously served as the lead U.S. State Department attorney for nuclear issues.