More than 100 experts on international law signed an open letter expressing what they described as serious concerns about violations of international law by the United States, Israel and Iran in the Middle East war. The letter was published in Just Security, an online journal based at New York University School of Law.

The experts wrote that the U.S.-Israeli decision to attack Iran was a clear breach of the United Nations Charter, which prohibits the use of force outside of self-defense or when authorized by the UN Security Council. The letter also pointed to what it called alarming rhetoric by officials, including President Donald Trump's threats to "obliterate" Iran's power plants.

"We are gravely concerned that the conduct and threats outlined here are causing serious harm to civilians and that they risk degrading the rule of law and fundamental norms that protect every nation's civilians," the signatories wrote. "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."

The letter took issue with Defense Secretary Pete Hegseth's statement that "no quarter" should be given for enemies. Denial of quarter in conflict means refusing to spare the life of anybody, even those who surrender or are wounded. The Department of Defense's own law of war manual forbids declaring that no quarter will be given.

Signatories included Harold Hongju Koh, a former legal adviser at the U.S. State Department; Oona A. Hathaway, a professor of international law at Yale Law School and president-elect of the American Society of International Law; and Jonathan Tracy, a former U.S. Army judge advocate.

The letter cited an attack on a primary school in Minab on the war's first day that reportedly killed at least 168 people, including 110 children. A growing body of evidence has suggested the strike was probably the result of a U.S. strike, according to investigators. The letter said the Minab school strike "likely violates international humanitarian law, and if evidence is found that those responsible were reckless, it could also be a war crime." The Department of Defense said it was investigating the incident.

Since the start of the conflict, 1,606 civilians, including at least 244 children, have been killed in Iran, according to the U.S.-based Human Rights Activists News Agency. Lebanon's health ministry said 1,345 people have been killed in Israeli strikes since March 2. Missile attacks on Israel launched from Iran and Lebanon have killed 19 civilians since the start of the war, according to Israeli emergency services. Local authorities in Gulf states reported at least 24 people killed in Iranian attacks, most of them security personnel or foreign workers, including 12 in the United Arab Emirates, seven in Kuwait, two each in Oman and Saudi Arabia, and one in Bahrain.

In response, the White House said Trump was "making the entire region safer and more stable by eliminating Iran's short- and long-term threats to the United States and our allies" and dismissed the letter's authors as "so-called experts." The White House accused Iranian authorities of "maiming and killing Americans, acting as the primary state sponsor of terror and brutally murdering its own people for merely speaking out against its oppressive rule" for the past 47 years.