FALMOUTH — During the time of its maximum influence, the Islamic State in Iraq and Syria (also known as ISIS) engaged in shocking forms of mayhem – beheadings, maiming and mutilation, the destruction of entire communities. ISIS also attacked and destroyed important cultural sites in Iraq and Syria, including churches, mosques and libraries in Mosul, and the ancient cities of Nimrud, Hatra and Palmyra. This war on culture was fueled in part by the expectation of financial gain. Objects taken from important cultural sites were sold on the black market for many millions of dollars, which in turn supported ISIS’ political and military objectives. But the war on culture was also deeply ideological, fueled by religious and political ideas and a perverse and deeply disturbing form of cruelty.

Cruelty directed toward actual, living individuals and groups certainly outweighs cruelty directed toward cultural artifacts and traditions, and as we think about real and potential conflicts around the world, the threat to human life is naturally our first concern. And yet the destruction of culture and the destruction of living individuals and groups are of a piece. Culture is what makes individual and collective lives meaningful; it is the outward, visible expression of who we are and what we care about. Tyrants and totalitarian regimes have always understood this. And the soldiers of ISIS knew it when they brought their sticks of dynamite to Palmyra and their torches to Mosul. To subjugate others, to inflict maximum cruelty upon them, you must rob them of their culture and their history.

In a flurry of recent tweets, President Trump has threatened Iran with the destruction of its cultural heritage. In a presidency that never ceases to amaze, these pronouncements should astonish us for several reasons:

First, the president’s threats violate standing international agreements regarding the preservation of cultural heritage, including the 1954 Hague Convention for the Protection of Cultural Property in the Event of Armed Conflict and the more recent Resolution 2437 of the United Nations Security Council. The United States was a principal participant in the crafting of these and other agreements regarding the preservation of cultural heritage in times of war.

Second, the United States government has been actively involved in the protection of cultural sites and artifacts in the Middle East for nearly two decades. During my time as chairman of the National Endowment for the Humanities, the agency joined with the U.S. State Department and a number of nongovernmental organizations in efforts to thwart illegal trafficking in stolen artifacts and to document important cultural sites that were under attack or threatened with attack by ISIS. During and after the second Iraq War, the agency made grants to assist preservationists in Iraq in their efforts to keep important museum and library collections out of harm’s way. Military commanders and units in Iraq, Syria and Afghanistan were trained in international protocols and made significant efforts to protect important cultural sites and artifacts, consistent with their primary military missions and responsibilities.

Finally, the remarkable cultural sites and resources in the Middle East, including Iran, are important not simply or exclusively to the countries in which they are found and where they were produced, but also to the human community. As significant and indeed irreplaceable records of human achievement, failure and – yes, sometimes – cruelty, these resources belong to all of us; they are part of our common human heritage.

Notwithstanding its recent disruptive and destructive behavior, Iran has a cultural history that is widely and rightly admired around the world. I recall vividly my first visit to the Freer-Sackler Gallery of the Smithsonian Institution in Washington, where its then-director, Julian Raby, acquainted me for the first time with the museum’s collection of ancient Iranian silverwork and ceramics. I was astonished by their beauty and intricacy. I am certain that visiting Persepolis and the other great ancient sites of Iran would generate equally powerful sensations. In this way, cultural preservation and appreciation provides an important bridge – perhaps the only dependable bridge – between different and sometimes conflicting cultural traditions.

I doubt that President Trump knows or cares much about Iranian culture and history. And I doubt that he knows or cares much about the considerable efforts that have been made over the past 200 years or so to protect cultural heritage in times of war. But his threat to attack the cultural sites of Iran suggests that he understands all too well how painful the loss of cultural heritage and common history can be. That he threatens nonetheless should be deeply disturbing to everyone who cares about traditional American values and the human community to which we always, and inescapably, belong.

This has nothing to do with our differing views on Iran, or how we protect American interests, or how we pave the way for peace and reconciliation in the Middle East. We can and always will have sharp disagreements about these matters. Despite these disagreements, what most of the world has come to agree upon is that there must be limits to armed conflict. We should not torture prisoners; we should not attack unarmed civilians; and we should not attempt to destroy people’s cultures and cultural heritage. It is a national tragedy of the first order that we have elected a president who does not understand or respect these limits.