Australian scientist Mark Oliphant helped push the development of nuclear weapons during World War II but later riled at US attempts to keep the UK and others out of the nuclear arms race.
The treaty to stop the proliferation of nuclear weapons has been exceptionally successful. Only nine states have them. Now, efforts are underway to completely rid the world of them.
What are the implications of North Korea's claims to have detonated a thermonuclear weapon?
From the air and on the ground: the reporters who told the HIroshima and Nagasaki stories to the American public.