After June 21, when the US bombed critical nuclear sites in Iran, some members of Congress called the mission illegal. It appears the hostilities have ended for now. But the legality of “Operation Midnight Hammer” is still debated.

The question boils down to three issues: Was the US entitled under international law to enter the war? Did President Trump have authority under US law to order the use of military force? And did the undertaking comply with the United Nations International Atomic Energy Agency (IAEA) requirement to protect nuclear facilities?

When a US ally is subject to an armed attack or “imminent” armed attack, the US may lawfully assist the ally’s defense. The authority for the intervention is enshrined in Article 51 of the United Nations Charter, which guarantees “the inherent right of individual or collective self-defense.” The multinational military incursions in Kuwait in 1991 and Afghanistan in 2001 were considered valid acts of collective self-defense.

Israel suffered two forms of Iranian armed attack. Iran orchestrated armed attacks on Israelis for decades through terrorist proxy groups based in territories surrounding Israel. And Iran directly attacked Israel with two waves of missiles and drones in 2024. Meanwhile, Iran posed an imminent threat of attack because it was becoming a nuclear threshold state while obsessively threatening to annihilate Israel.

Iran observers are unsure how close the regime came to nuclear weaponization. The bomb-making task requires highly enriched uranium, a triggering device, and a delivery vehicle such as a ballistic missile. On April 17, IAEA Director General Rafael Grossi warned that Iran had all the weaponizing “puzzle pieces” and was “not far” from putting them together.

Two months later the IAEA reported that Iran had illegally stockpiled over 400 kg of highly enriched uranium, enough to make several nuclear bombs. Estimates on the remaining time needed to complete the lethal puzzle ranged from months to a year.

Some critics of the American-Israeli collective self-defense welcomed the erasure of Iran’s nuclear facilities but insisted President Trump lacked authority to order the operation without a Congressional declaration of war under Article I of the Constitution. The executive and legislative branches of the US government have long debated the Constitutional power to declare war, and the courts have never resolved the standoff.

A 2016 Department of Justice report formalized the executive branch position on the Constitutional dispute. It defines “war” for the purposes of Article I as a prolonged and substantial military engagement. If there’s no war, there’s no need for a declaration of war. For example, the DOJ opined that a two-week air campaign involving 2,300 combat missions, and an air campaign involving over 600 missiles and precision-guided munitions, did not amount to wars.

Under the DOJ framework, the June 21 assault on Iran’s nuclear program was certainly not a war. The counterproliferation scheme involved just 75 precision guided weapons in a one-day surgical strike. Seven US Air Force B-2 stealth bombers in a “package” of 125 aircraft dropped less than 20 bombs on two nuclear sites, and a US submarine fired dozens of Tomahawk missiles at a third nuclear site. The pilots spent only two and a half hours in Iranian airspace.

Members of Congress who raised the Constitutional challenge also claim that the president violated the War Powers Resolution of 1973 (WPR). Under the WPR, the president may commit armed forces to “hostilities” only if there is a Congressional “declaration of war,” a “specific statutory authorization,” or a “national emergency” created by an attack on the US or its armed forces. Once the military action starts, the president must report to Congress within 48 hours and must stop the action within 60 days unless Congress gives its approval.

Presidents of both parties have repeatedly ignored the three WPR prerequisites to the use of military force. Congressional acquiescence was treated as consent. In the tacit understanding, a president may initiate armed force if it is more surgical than “war” as defined by the DOJ framework and it serves “important national interests.” Consistent with that policy, President Trump described the June 21 action as “a precision strike” that served “vital United States interests.” The vital US interest was the same one emphasized by every US president since 2003, when the IAEA first disclosed Iran’s clandestine plan to develop nuclear weapons. President Trump said the violently anti-Western regime must never acquire a nuclear bomb.

Assuming the US raid in Iran was validly authorized, the only remaining question is whether it was validly implemented. IAEA standards prohibit attacks on nuclear facilities “devoted to peaceful purposes.” Director General Grossi stressed this point in his June 13 Statement on the Situation in Iran, while calling for a diplomatic solution to the Israel-Iran conflict.

Significantly, the Statement did not say Iran’s nuclear facilities were peaceful. Nor did it accuse Israel of violating any IAEA rule. The military nature of Iran’s nuclear facilities made them legally targetable for attack.

It is not legally clear when a US president may wield military might. But based on the written law and past US practice, Operation Midnight Hammer was a valid use of force.

Joel M. Margolis is the Legal Commentator, American Association of Jewish Lawyers and Jurists, U.S. Affiliate of the International Association of Jewish Lawyers and Jurists. His 2021 book, The Israeli-Palestinian Legal War, analyzed the major legal issues in the Israeli-Palestinian conflict. Previously he worked as a telecommunications lawyer in both the public and private sectors.

The post The US Attack on Iran Was Legal first appeared on Algemeiner.com.