President Donald Trump is often incautious in his language when speaking on the international stage. Words matter in diplomacy which often reflect important distinctions of international law. President Trump’s latest tweet is an example of this pattern. In pledging to strike back “very fast and very hard” to any Iranian retaliation for the killing of Iranian General Qassem Soleimani, Trump included striking Iranian cultural sites. Under international law, the targeting of cultural targets is viewed as a war crime. The U.S. military has a long history of avoiding such targets.

Trump tweeted:

“Let this serve as a WARNING that if Iran strikes any Americans, or American assets, we have targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD.”

The President could fairly argue that he was referencing to legitimate military targets that also have cultural value. However, with a possible war imminent, it is even more important for the President to take care in the language that we use to justify any response to Iran.

Protocol I of the Geneva Conventions it is prohibited to “commit any acts of hostility directed against the historic monuments, works of art or places of worship which constitute the cultural or spiritual heritage of peoples…to use such objects in support of the military effort…[and] to make such objects the object of reprisals.”

The Hague IV requires:

In sieges and bombardments all necessary steps must be taken to spare, as far as possible, buildings dedicated to religion, art, science, or charitable purposes, historic monuments, hospitals, and places where the sick and wounded are collected, provided they are not being used at the time for military purposes.

It further states:

Art. 56. The property of municipalities, that of institutions dedicated to religion, charity and education, the arts and sciences, even when State property, shall be treated as private property.

All seizure of, destruction or willful damage done to institutions of this character, historic monuments, works of art and science, is forbidden, and should be made the subject of legal proceedings.

Other international resolutions and agreements amplify this long-standing principle. In 2017, the United Nations condemned in resolution 2347 “the unlawful destruction of cultural heritage, including the destruction of religious sites and artefacts, and the looting and smuggling of cultural property from archaeological sites, museums, libraries, archives, and other sites, notably by terrorist groups.”

The targeting of cultural sites would violate not just international but American values. Indeed, in World War II under the Truman Administration, the U.S. decided not to bomb Kyoto (made at the urging of Secretary of War Henry Stimson) due to its historic and religious significance.

This is why such statements by the President can be damaging to our effort to build a coalition to face any Iranian retaliation. I was hoping that Secretary of State Mike Pompeo would clarify this point on CBS Face the Nation but the issue of threatening cultural sites did not come up. Jake Tapper raised it on CNN with Pompeo, but Pompeo seemed to brush it aside. It should be clarified by the Administration as we head into a highly dangerous period with Iran.