A stupefied world learned Tuesday night that President Donald Trump wasn’t joking, he was serious, about wanting to buy Greenland—so serious that when the Danish prime minister told him it wasn’t for sale, he canceled a long-scheduled trip to Denmark and tweeted, in a very pissy tone, that he called off the visit because of her refusal.

He thereby revealed that he’d lined up the trip in the first place not to discuss a host of foreign policy issues—Denmark is one of the smallest, but also among the most loyal U.S. allies—but rather to wrangle a modern-day Louisiana Purchase.

We can joke about the episode’s resemblance to one of the Onion’s wilder satires. We can shudder over the sheer daftness of this man who holds the fate of the world in his hands. But we should also consider what the tale suggests about the way Trump looks at the world—and what that implies about his utter unsuitability for the office of the presidency.

One implication of this head-spinning tale is that Trump has not even remotely begun to make the transition from real estate magnate to statesman.

Trump made the point himself. On Sunday, reporters asked him about a story in Friday’s Wall Street Journal that he was thinking about buying the largely frozen island, which is an autonomous territory of Denmark. He confirmed that the story was accurate, describing the idea this way: “Essentially, it’s a large real-estate deal.”

The Journal reported that the idea has been whirring around in Trump’s brain since the spring, when one of his associates happened to say at a dinner that Denmark was having a hard time keeping up with its annual $600 million subsidy to keep Greenland solvent. Trump, instinctively seeing this as a bargain akin to buying an undervalued property, asked if it would be possible to buy the place. Under most presidencies, the remark would have been laughed down. But since Trump has taken care to surround himself with sycophants, some of the aides scurried to research the notion.

It is in Trump’s nature to think this way. One reason he became enamored with Kim Jong-un is that North Korea—as he put it earlier this year—is “all waterfront property,” adding, “It’s a great location, as we used to say in the real estate business.”

Trump may well be aware that Greenland is also rich in minerals and other natural resources and is likely to become more so as its icy surface melts due to global warming. Trump also said at his impromptu Sunday news conference that buying Greenland would also be “strategically … nice,” and he almost has a point there.

During the Cold War, a major focus of U.S. naval strategy was the “G-I-UK gap,” the wide strait of water in the North Atlantic separating Greenland, Iceland, and the United Kingdom. As long as the Soviet navy could be contained behind that gap, it would remain a merely regional force; but if it broke through, it could endanger trans-Atlantic shipping and disrupt U.S. supplies to NATO allies in the event of war.

In recent years, the melting of the polar ice caps has revived strategic thinking about the Arctic as a shipping route—sparking economic competition among the United States, Russia, and Japan—and as a possible theater for military conflict.

To the extent that this is a matter of grave concern for national security (and let’s stipulate, for the moment, that it is), this is why large nations have allies—to enhance security and pursue common interests. The U.S. and Denmark have many common interests; Denmark has long been an eager ally of the United States, even sending troops to fight and die in the Iraq and Afghanistan wars. If Greenland’s resources are valuable, most presidents would engage in trade; if the country has geostrategic importance, most presidents would conduct diplomacy to make sure it stays on America’s side. Neither the first nor last impulse of most presidents would be to wonder how much the place costs.

Trump has not even remotely begun to make the transition from real estate magnate to statesman.

But Trump is not like most presidents. He has no feel for, or interest in, diplomacy. This is another lesson of this absurd tale that reveals—or rather, confirms—Trump’s lack of talent at his current job.

In fairness, President Harry Truman put out feelers to buy Greenland in 1946, but backed off when Denmark evinced no interest. Even so, both bids—Trump’s and Truman’s—are anomalies in modern history. No nation has bought a chunk of territory from another country since 1917, when the United States bought the U.S. Virgin Islands from (coincidentally) Denmark.* Before then, the U.S. bought Alaska from Russia in 1867, La Mesilla from Mexico in 1853, and Louisiana from France in 1803. The only other country to engage in this sort of transaction has been Canada, which bought Rupert’s Land from the Hudson Bay Company in 1868.

Even if the idea of imperial purchases were revived, Greenland is not Denmark’s to sell: It is an autonomous territory of the Danish kingdom, which continues to control Greenland’s national security policies. But since a home-rule law passed in 1979, Greenland has elected its own Parliament and has run its domestic affairs.

Denmark’s prime minister, Mette Frederiksen, affirmed this when she first heard of Trump’s interest in buying the territory. “Greenland is not Danish, Greenland belongs to Greenland,” adding, “I strongly hope that this is not meant seriously.”

When she realized Trump was serious, she called the notion “absurd” and said she had no interest in selling even if she could. Greenland’s foreign ministry added, in a tweet, that the country is “open for business but not for sale.”

This is what agitated Trump’s Twitter thumbs Tuesday night. In a thread, he wrote:

Denmark is a very special country with incredible people, but based on Prime Minister Mette Frederiksen’s comments, that she would have no interest in discussing the purchase of Greenland, I will be postponing our meeting scheduled in two weeks for another time. The Prime Minister was able to save a great deal of expense and effort for both the United States and Denmark by being so direct. I thank her for that and look forward to rescheduling sometime in the future!

This was news to Carla Sands, the U.S. ambassador to Denmark, who had tweeted just two and a half hours earlier, “Denmark is ready for the POTUS @realDonaldTrump visit! Partner, ally, friend.”

To the Danes, this is more than merely embarrassing. A headline in the conservative newspaper Berlingske read: “The U.S. and Denmark’s relationship has never been this ice-cold. It will have wide-ranging consequences.”

On Wednesday, speaking to reporters on the White House lawn, Trump deepened the freeze, denouncing the Danish prime minister as “nasty” for calling his idea “absurd.” Trump railed, “She’s not talking to me, she’s talking to the United States of America.”

It was unimaginable before Trump that U.S.-Danish relations could get icy. But many things were unimaginable before Trump, and the intensification of America’s isolation in the world, to this degree, is one of them.

Correction, Aug. 21, 2019: An earlier version of this article misstated that Japan had purchased the Senkaku Islands from another country. They were purchased from private owners.