The operative document here is the United Nations’ 1954 Hague Convention. It prohibits using monuments and sites for military purposes and harming or misappropriating cultural property in any way. The presence of a distinctive blue shield indicates cultural property placed under the Convention’s protection.

But a blue shield wouldn’t have done anything for the Mosul Museum. A U.N. document that prohibits targeting cultural heritage is powerless in the face of nonstate actors dedicated to doing exactly that. The laws of war were changed after World War II in response to the genocidal impulses of the Nazis—the 1945 London Convention introduced the concept of “crimes against humanity.” Today they need to be changed again in hopes of stopping the current onslaught, or at least preventing subsequent ones.

Some might argue that it would diminish the moral force of a concept like crimes against humanity to include inanimate objects in the same law. In fact, they already are included. The London Convention prohibits “plunder of public or private property, wanton destruction of cities, towns or villages, or devastation not justified by military necessity.” Updating it now to mention cultural heritage specifically would simply make an implied protection explicit, bringing existing intentions in line with current realities.