At least twice before that transaction, the U.S. had mulled buying Greenland, first as part of an unsuccessful plan in 1867 proposed by Secretary of State William H. Seward, who is now most remembered for buying Alaska from Russia in the same year.

Danish Prime Minister Mette Frederiksen says an American takeover of Greenland would amount to the end of the NATO military alliance.

U.S. Secretary of State Marco Rubio on Wednesday said that he would meet with Denmark next week, as U.S. President Donald Trump has repeated in recent days that he wants to gain control of Greenland.

Donald Trump has again proposed annexing Greenland, after Denmark's leader urged him to "stop the threats" over the island. Speaking to reporters, the US president said "we need Greenland from the standpoint of national security".

Denmark and Greenland are seeking a meeting with U.S. Secretary of State Marco Rubio after the Trump administration reiterated its intention to take Greenland.

Katie Miller, the wife of President Trump's deputy chief of staff Stephen Miller, posted an image of Greenland covered by the U.S. flag on X.

Seven European countries have issued a joint statement saying only Greenland and Denmark can decide on their future.

Only Denmark and Greenland can decide questions about the future of the Arctic island, Canadian Prime Minister Mark Carney said on Tuesday when asked about U.S. threats of annexation.

Analysts say the Cold War agreement allows the president to increase the American military presence almost at will.