As Prime Minister of Estonia, Kaja Kallas has ardently supported Ukraine’s defense even before the invasion -- giving the most weapons per capita of any European country. Dubbed 'The Iron Lady' of Europe, Kallas is in London meeting with British Prime Minister Boris Johnson as his political survival is on the line. Christiane sat down with her in London. Also on today's show: tennis star Rafael Nadal, author Vauhini Vara. To learn more about how CNN protects listener privacy, visit cnn.com/privacy