Donald Trump spent a noteworthy chunk of the transition period provoking controversy—and insulting NATO allies—with his proposals for expanding the U.S. Maybe most prominently, he has repeatedly discussed buying Greenland from Denmark,

From the Reconstruction era to the Cold War, multiple administrations have tried (and failed) to acquire the Arctic island. Here’s why Greenland has always remained out of reach—and why it always mattered so much.

U.S. President Donald Trump on Monday said the United States needs to control Greenland to ensure international security. Trump made the comments while signing executive orders in the Oval Office of the White House on the first day of his second term as president.