Japanese PM faces dilemma at G7 as he balances anti-nuke goals with reality of threats

HIROSHIMA: 8:15 on the morning of Aug. 6, 1945.

It's a big reason leaders from the world's most powerful democracies descended on Hiroshima for this weekend's Group of Seven summit: Part commemoration, part effort to confront the continuing consequences of the moment a US B-29 Superfortress released what the Americans named "Little Boy" over the city in the first wartime use of a nuclear bomb.