During World-War-Two, Japan's imperial army killed around 300,000 Chinese people within a six-week period in China's former capital, Nanjing.
China's foreign minister, Wang Yi says the victims who died at the hands of Japanese soldiers are also worthy of remembrance.
"Hiroshima is worthy of attention. But even more, Nanjing should not be forgotten. Victims deserve sympathy, but perpetrators should never shirk their responsibility," he said.