Throughout his presidency, President Trump has repeatedly attempted to distinguish between the “wonderful Iranian people” and their “hostile,” “brutal and corrupt” leadership.

But as he suggested the possibility of retaliatory strikes against Iran on Saturday, he resorted to a threat that — in prior conflicts — has deliberately blurred the distinction between countries’ regimes and their people.

By suggesting strikes on “52 Iranian sites,” including some that are important to “the Iranian culture,” Trump threatened a way of waging war that has drawn growing outrage in recent decades, critics argued Monday.

Such attacks have been condemned as “cultural cleansing” by Irina Bokova, a former director general of the U.N. Educational, Scientific and Cultural Organization (UNESCO). “The deliberate destruction of heritage is a war crime,” she told the U.N. Security Council in 2017, adding that “it has become a tactic of war to tear societies over the long term.”

Bokova was primarily referring to the destruction of cultural sites by militant groups at the time, but to some, her words appear eerily relevant for Iran, which has 22 cultural UNESCO World Heritage Sites, including the ancient ruins of Persepolis, with its palatial buildings and terraces.