President Trump reportedly held a “fiery” call with Denmark’s Prime Minister Mette Frederiksen over the president’s insistence that U.S. control of Greenland is necessary for American national security.

Donald Trump insisted he was serious in his determination to take over Greenland in a fiery telephone call with Denmark’s prime minister, according to senior European officials.

Denmark’s Prime Minister Mette Frederiksen has called the country’s business leaders to a meeting on Thursday after US President-elect Donald Trump last week threatened military or economic action such as tariffs to take control of Greenland.