President Trump threatened Friday to use tariffs to win global assent to the US acquiring Greenland — after Denmark insisted again this week that it won’t sell the world’s largest island to the United States. "I may put a tariff on countries if they don't go along with Greenland, because we need Greenland for national security. So I may do that," Trump said at the White House. Trump, who has styled himself the "tariff king," made the remark while touting his use of threatened import levies to secure his "most favored nation" drug price equalization with other countries.