<p>Cuba's leader is defiant in the face of the country's worst humanitarian crisis in decades, while President Trump hints at inflicting more pain. And the Strait of Hormuz is the latest of many maritime chokepoints which, in the past, have destroyed or saved civilisations. </p><p>        Guests:</p><ul><li>Jon Lee Anderson, staff writer with The New Yorker</li><li>Damien Valdez, historian from the University of Cambridge</li></ul>