Over 100 International Law Experts Warn: U.S. Strikes on Iran Violate UN Charter and May Be War Crimes

The United States and Israel initiated strikes on Iran over one month ago, on February 28, 2026. The attack was a clear violation of the United Nations Charter. The conduct of the war, and statements of U.S. officials, also raise serious concerns about violations of international humanitarian law, including potential war crimes. We have written the below statement together with over 100 U.S.-based international law experts, to detail our profound concerns about the war. The letter is signed by international law experts across the United States, including senior professors; leaders of prominent international law associations, non-governmental organizations, and legal clinics; former government legal advisors; and military law experts and former Judge Advocates General (JAGs).

Letter of over 100 international law experts on Iran war:
We, the undersigned U.S.-based international law experts, professors, and practitioners write to express profound concern about serious violations of international law and alarming rhetoric by the United States, Israel, and Iran in the present armed conflict in the Middle East.

Due to our connection to the United States, our focus here is on the conduct of the U.S. government, but we remain concerned about the risk of atrocities across the region including the continuing risks posed by the Iranian government to Iranians through violent crackdowns on dissent, and to civilians across the Middle East through Iran’s ongoing unlawful strikes on civilian infrastructure using explosive weapons in densely populated areas. One month has passed since the United States and Israel launched strikes across Iran. The initiation of the campaign was a clear violation of the United Nations Charter, and the conduct of United States forces since, as well as statements made by senior government officials, raise serious concerns about violations of international human rights law and international humanitarian law, including potential war crimes.

We collectively affirm the importance of equal application of international law to all, including countries that hold themselves out as global leaders. Recent statements from senior U.S. government officials describing the rules governing military engagement as “stupid” and prioritizing “lethality” over “legality” are profoundly alarming and dangerously short-sighted. These claims, particularly in combination with the observable conduct of U.S. forces, are harming the international legal order and the system of international law that we have devoted our lives to promoting. The war, which is costing U.S. taxpayers between $1-2 billion each day, is imposing significant harm to civilians in the region, has resulted in the loss of hundreds of civilian lives across the Middle East, and is causing serious environmental and economic harms.

We write to express our concern about 1) jus ad bellum, or the decision to go to war, 2) jus in bello, or the conduct of hostilities, 3) rhetoric and threats from senior U.S. officials and their allies, which portend further abuses, and 4) the decimation of civilian harm mitigation structures within the U.S. government as a part of U.S. Secretary of Defense Pete Hegseth’s “gloves off” approach to warfare.

(Covered in detail)

1. Jus ad bellum concerns:
2. Concerns about violations of international humanitarian law
3. Concerns about rhetoric and threats from senior officials
4. Concerns about institutional safeguards against further violations

We are gravely concerned that the conduct and threats outlined here are causing serious harm to civilians in the Middle East, and that they also contribute to escalating the conflict, damaging the environment and the global economy, and that they risk degrading the rule of law and fundamental norms that protect every nation’s civilians. Public statements by senior officials indicate an alarming disrespect for the rules of international humanitarian law accepted by states, and which protect both civilians and members of the armed forces.

https://www.justsecurity.org/135423/professors-letter-international-law-iran-war/