Last year, Pope Francis met with several survivors on visits to Hiroshima and Nagasaki, paying tribute to the "unspeakable horror.
The first atomic bomb was dropped on the western city of Hiroshima on August 6, 1945 by the US bomber Enola Gay.
Survivors, relatives and a handful of foreign dignitaries attended this year's main event in Hiroshima to pray for those killed or wounded in the bombing...
"A strong sense of anxiety is spreading across the globe that in the not too distant future these weapons could actually be used again,"
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