China recently sought to bankroll the construction of three airports in Greenland, drawing concern from then-Defense Secretary Jim Mattis and prompting the Pentagon to make the case to Denmark that it should fund the facilities itself rather than rely on Beijing.
What he wasn't tweeting about was his reported interest in buying Greenland.
Politicians in Denmark have ridiculed the idea of a possible United States acquisition. "Forget it", Danish Conservative MP Rasmus Jarlov wrote on Twitter.
"The United States has a compelling strategic interest in Greenland, and this should absolutely be on the table", he tweeted.
"We are talking about real people and you can't just sell Greenland like an old colonial power", he told Reuters.
"They tried to buy us in 1867, during Second World War, and now they are trying again", local Kulusuk resident Bent Abeelsen told CNN.
Reasons why Trump might want to buy Greenland. "Totally out of season", former prime minister Lars Lokke Rasmussen said on Twitter.
She is set to visit Greenland this weekend and has said she is "very much looking forward" to it.
Trump is due to visit Copenhagen in September and the Arctic will be on the agenda during meetings with the prime ministers of Denmark and Greenland, an autonomous Danish territory. In earlier periods purchase of sovereign territory was common The US bought Louisiana from France in 1803 for $15 million.
There is precedence set to land transfer as Alaska was also purchased from Russian Federation back in 1867 for $7.2 million.
The question "How to buy a Country" and "Is Greenland for Sale" has come up as President Trump has shown interest in purchasing Greenland. The US bought the US Virgin islands from Denmark in 1917.
"An outright sale would have to be approved by the United States, Denmark, and the people of Greenland, and the odds of that seem vanishingly small", he added.
Gagnon revealed that an acquaintance formerly stationed at the base went back and "interviewed indigenous people there who tell stories about a USA nuclear weapon that fell from a plane, or was in a plane crash, and the locals were hired to clean up the contamination".
Greenland Premier Kim Kielsen has not commented publicly on the reports about Mr Trump.
But no official move was made until 1946, when Harry Truman offered Denmark $100m for the territory.
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