Cotton is right: In the 19th century, the United States bought large chunks of land from European powers as it expanded south and west. What he doesn’t acknowledge is that in buying that land, the United States also took control of the native peoples—Sioux, Pawnee, Cheyenne, Crow, Seminole, Apache, and Inuit, among many others—who were living on it. And it did so without their consent. The only treaties that mattered were with the distant governments selling the territories in question.

Since then, the notion that white governments can treat nonwhite peoples as commodities—to be traded alongside the land on which they live—has gone out of style. In 1960, amid movements for independence in Africa and Asia, the United Nations General Assembly declared that “the subjection of peoples to alien subjugation, domination and exploitation constitutes a denial of fundamental human rights.”

That’s why Denmark can’t sell Greenland. Although originally subjects of the Danish crown, Greenlanders have gained self-government as colonialism has receded across the world. In 1979, the island acquired its own Parliament and control of its health-care system and schools. In 2008, Greenlanders voted to make Greenlandic—an Inuit language—the island’s official language and to claim a larger share of the revenues produced by the island’s natural resources. Greenland has not opted for independence. But as Danish Prime Minister Mette Frederiksen explained in response to Trump’s offer, “Greenland is not Danish. Greenland is Greenlandic.”

Greenland’s destiny is in its own people’s hands. And they appear to have little interest in becoming part of the United States.

Why doesn’t that matter to Trump? Because colonialism appeals to him.

Read: Denmark learns what it’s like to be at the center of Trump’s attention

He’s repeatedly lionized General John Pershing for supposedly crushing a Muslim rebellion in the Philippines by dipping bullets in pigs’ blood. The story is false, but the war in which it purportedly occurred was real. That war—in which the United States brutally repressed the Filipino struggle for independence after seizing the territory from Spain in 1898—marked the dawn of American overseas colonialism. That Trump glorifies it is telling.

Trump has also repeatedly declared that after invading Iraq, the United States should have taken its oil. Doing so would have confirmed the suspicions of America’s critics, who saw the war as an imperial venture designed to rob Iraq of its natural resources. But Trump sees no problem with that.

Again and again, he has disregarded the principle that people who live in a given territory should control who governs it. In 2014, when Russia invaded and then annexed Crimea, which had been part of Ukraine, the United States imposed sanctions because Moscow had violated two core principles of the post–World War II order: Nations should not claim territory without the consent of the people living in it, and they should not do so by force. (Russia later sought to validate its seizure of Crimea with a plebiscite that neither the European Union nor the United States accepts as legitimate.) In 2016, however, Trump suggested that he might recognize Russia’s annexation. And in the years since, he’s repeatedly proposed readmitting Moscow to the G7 club of nations, which expelled it after the Crimea invasion.