Trump reportedly wants to buy Greenland. So did the Truman administration.

Should the United States buy Greenland from Denmark?

It’s something that President Donald Trump has repeatedly asked his staff to explore in recent weeks, bewildering top aides. But he’s not first to ponder the question, which was first floated in the 1860s, when a report commissioned by the State Department under President Andrew Johnson concluded that the icebound island’s abundance of fish and mineral resources could make it a valuable investment.

And in 1946, President Harry Truman's administration went even further, offering to purchase Greenland from Denmark in exchange for $100 million in gold.

"People have forgotten about how important places like Greenland were in the Cold War," said Ronald Doel, an associate professor of history at Florida State University and a co-editor of "Exploring Greenland: Cold War Science and Technology on Ice."

[Greenland to Trump: We are not for sale]

These days, Doel told The Washington Post, Greenland is most commonly thought of as a canary in the coal mine when it comes to climate change, given the threats it faces at a time of melting glaciers and rising seas. But not too long ago, “it was a really different calculus.”

In the late 1940s, the Soviet Union had just become the United States' main adversary. The shortest distance between the two rival powers was over the North Pole, and the Arctic region started to look like a potential battleground. Greenland sat practically dead center between the population centers of the United States and several major cities in the U.S.S.R. To Pentagon strategists, that made Greenland a valuable piece of real estate. If the Soviets launched an attack, American bombers stationed on the island would already be halfway to Moscow.

That wasn't the only reason the Defense Department was shopping around for land in the Arctic. The possibility of conflict playing out in frozen polar regions meant that the American military had to figure out if its weapons and monitoring systems would even work in frigid climates. As Doel and his co-editors write in "Exploring Greenland," researchers weren't quite sure how the northern lights, known as the aurora borealis, would affect navigational equipment and radio dispatches, or if the ice cap would muffle the seismic signals if the Soviets conducted nuclear tests.

By 1946, "practically every member" of the planning and strategy committee of the Joint Chiefs of Staff agreed that the United States should try to buy Greenland, John Hickerson, a State Department official, wrote in a memo. The consensus among the group was that the territory was "completely worthless to Denmark," he reported, and "indispensable to the safety of the United States."

Denmark had other thoughts on the matter. After floating the proposal at the December 1946 meeting in New York, Secretary of State James Byrnes wrote in a telegram that his overture "seemed to come as a shock" to Danish Foreign Minister Gustav Rasmussen. The small Scandinavian nation likely could have used the money, but it also had its pride.

"It was seen as a bit of an insult," Doel told The Post.

The rejected offer didn't become public knowledge until 1991, when a Copenhagen newspaper came across declassified documents in the National Archives. But rumors that the U.S. might annex Greenland occasionally popped up during the 1940s, with newspaper columnists debating whether it would be a smart strategic move or a wasteful way of adding to the national debt.

In 1945, the famed Arctic explorer Peter Freuchen, while visiting Twin Falls, Idaho, on a speaking tour, was asked if he thought the United States should purchase Greenland. His response was a flat out no, the Times-News reported: "He feared the natives would be treated as are the Eskimos in Alaska, which he definitely didn't favor because he said U.S. standards breed discontent among natives."

Historians haven't documented what Greenland's indigenous peoples thought of the proposal, or if they were even consulted. The declassified State Department memos don't make any mention of their existence, noting only that about 600 Danish people lived on the island. (Today, roughly 58,000 people live in Greenland, the majority of whom are Inuit.) A 1947 Time magazine article summed up the prevailing attitudes when it referred to Greenland as "the world's largest island and stationary aircraft carrier."

Ultimately, Denmark's refusal to sell Greenland to the United States wasn't a major obstacle. In 1951, the two countries entered into a defense treaty that allowed the Pentagon to build Thule Air Base, its northernmost military installation and one of the largest ever constructed, in what had once been one of the most remote outposts on the planet. (To make room, the Danish government displaced Thule's indigenous Inughuit community, whose members were "dropped off unceremoniously with blankets, tents and the very best of wishes in 'New Thule,' some sixty-five miles north," historian Daniel Immerwhar writes in "How To Hide an Empire: A History of the Greater United States.")

And though Denmark's government hasn't suggested that it would be interested in putting Greenland up for sale, the notion of a U.S. takeover has reared its head occasionally since then. In the 1970s, Vice President Nelson Rockefeller reportedly suggested buying Greenland for its mineral resources, and in 2001, an editorial in the conservative National Review suggested, somewhat jokingly, that purchasing Greenland would eliminate the need to negotiate with Denmark about missile-defense systems.

“And if this whole global-warming thing turns out to be worse than expected, at least we’ll all have a place to live,” reporter John J. Miller concluded.