John Bolton served as US national security adviser during Donald Trump's first presidency and as US ambassador to the United Nations under George W. Bush.

Bolton and Trump fell out spectacularly with the publication of Bolton's 2020 memoir, "The Room Where It Happened." He has since been a persistent Trump critic.

DW asked him whether America was winning its war in Iran and whether he saw Reza Pahlavi, the exiled son of Iran's last shah, as a credible future leader of Iran.