Could European Nato members use their large holdings of US shares and bonds to put pressure on America? It’s a question that some in Europe found themselves asking as the geopolitical crisis over Greenland escalated and leaders desperately tried to think of ways to dissuade Donald Trump. It is true that trillions of dollars of American financial assets are held in Europe. But the devil, as ever, is in the detail. Tim Harford talks to Toby Nangle, a journalist with the Financial Times, to drill down into the numbers.

Presenter: Tim Harford Producer: Nathan Gower Series Producer: Tom Colls Editor: Richard Vadon Programme Coordinator: Brenda Brown Sound Engineer: James Beard