​Since returning to the White House, Donald Trump has made a string of expansionist foreign policy announcements, angering several of his international counterparts. After reiterating his ambitious intention to purchase Greenland, and renaming the Gulf of Mexico, the US president doubled down on his insistence that Washington should regain control of the Panama Canal, the essential shipping passage he claims has been commandeered by China. Built by the United States in the early twentieth century, the waterway transformed global trade and marked America’s emergence as a superpower on the world stage, before being transferred to Panamanian control via a 1977 treaty. So why has Donald Trump got it in his sights now?

On this episode Jonny Dymond speaks to Julie Greene, a professor of American studies at the University of Maryland, about the storied history of the Panama Canal. And the BBC’s North America business correspondent Michelle Fleury discusses the politics and economics behind the Trump administration's diplomatic pursuit of the trade route.

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Producers: Laurie Kalus, Mhairi MacKenzie and Beth Timmins

Sound engineer: Annie Smith

Assistant editor: Sergi Forcada Freixas

Senior news editor: China Collins