It has been nearly 80 years since the United States expanded its territory, and there are increasing signs that President Donald Trump intends to change that. After what seemed in his first term like a lark about claiming Greenland, Trump has doubled down on that and other expansionist ideas.

During last week's tense call with the Danish premier, Trump insisted he was serious about taking over Greenland, the Financial Times reported, raising fears about the future of trans-Atlantic relations.