In Nagasaki, U.N. Secretary-General Antonio Guterres underlined his solidarity with atomic bomb survivors, known as hibakusha, and called them "true messengers" of peace.

He acknowledged the power of hibakusha as he reminded the world from the city — one of the two in Japan subjected to atomic bombing — that the realization of a nuclear-free world is still distant, and that work toward disarmament continues.

"When we see nonproliferation at risk, and when we see a lack of commitment to disarmament, to amplify the voice of the hibakusha becomes more and more important," Guterres said in an interview ahead of the 73rd anniversary of the U.S. atomic bombing.