This week marks 70 years since the United States dropped two atomic bombs – within three days of each other – on two Japanese cities, Hiroshima and Nagasaki. Japan surrendered, and World War II ended. The American government and the military explanation has always been that those bombs – which killed more than 200,000 people upon impact – were necessary to avoid even bigger casualties among U.S. and Allied troops fighting Japan. That trade-off is still being talked about decades later. KCRW's Steve Chiotakis spoke with Junji Sarashina, a survivor of the Hiroshima atomic blast who lives in Orange County, and Susan Southard, author of the new book Nagasaki: Life After Nuclear War.