“Denmark can be a great ally, but you can’t treat Greenland, which they have operational control over, as some kind of backwater. It’s in the Western Hemisphere, multiple Presidents have tried to bring it into our sphere,” he told an interviewer last month.

Denmark said on Friday it meant seriously that Greenland is not for sale, after Secretary of State Marco Rubio said U.S. President Donald Trump's interest in acquiring the island was "not a joke". Trump says he will make the autonomous territory of Denmark a part of the United States,