The Financial Times reports that Trump threatened Denmark's prime minister in a "horrendous" 45-minute phone call. From the reportage, you get the impression that Mette Frederiksen hadn't considered the possibility Trump was serious about Greenland and wasn't briefed on how to address the subject.

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.

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.