U.S. President-elect Donald Trump says he wants to make Greenland a part of the United States and does not rule out using military or economic power to get Denmark to hand it over.

Denmark would need to offer Greenland to the UK first before the island could be sold to Donald Trump, it has emerged. An agreement dating back to 1917 means Britain has first refusal on the Arctic island if current owners Denmark decide to sell it, according to Tom Høyem, Copenhagen’s representative in Greenland from 1982 to 1987.