United States President Donald Trump, who built his career as a real estate tycoon, now has the world’s largest island in sight. He is reportedly eyeing the entire Greenland for purchase – an idea that has been met with ridicule in Denmark, which rules over the ice-covered island. One Danish leader said Trump has “gone mad”.

Greenland, the world’s largest island, is an autonomous territory under the Kingdom of Denmark. It is 50 times the size of Denmark’s mainland in Europe, but the number of people who live there is less than 1% of Denmark’s population. Greenland itself is part of North America.

According to a report in The Wall Street Journal, Trump has “with varying degrees of seriousness” asked his advisers in meetings and at dinners, whether the United States can acquire Greenland, and has asked his White House adviser to look into the idea. The newspaper was unable to get a comment from the White House or the State Department.

One adviser told the newspaper that Trump had brought it up at a dinner last spring. The president said he was told by someone that Denmark was having financial trouble giving assistance to Greenland, and if he could consider buying it. He asked: “What do you guys think about that? Do you think it would work?”

How serious Trump is about the idea is not clear. In 1946 too, President Harry Truman had offered to buy Greenland for $100 million, but Denmark had refused to sell it.

Trump is scheduled to meet the Danish and Greenlandic prime ministers in a visit to Copenhagen next month.

‘April Fool’s Day joke’

The Denmark government has not responded to the news yet.

Lars Lokke Rasmussen, a former prime minister of Denmark, tweeted that it must be an “April Fool’s Day joke, but totally out of season”. Soren Espersen, a spokesperson for the Danish People’s Party, told state broadcaster DR: “If he is truly contemplating this, then this is final proof that he has gone mad.”

Espersen added: “I must say it as it is: the idea that Denmark should sell 50,000 citizens to the US is completely insane.”

Greenland MP Aaja Larsen told Financial Times: “I don’t think it’s a good idea. I say no thank you to Trump.” Greenland sends two members to the Danish Parliament.

Martin Lidegaard, a former minister, tweeted: “Trump buy Greenland?! Hopefully it’s a joke, but otherwise it is a terrible thought, with the risk of the militarisation of Greenland and less independence for the Greenlandic people – besides being a great loss to Denmark.”