An association of U.S. diplomats has given its Constructive Dissent Award to a U.S. official who persuaded the State Department to stop boycotting the annual Hiroshima Peace Memorial Ceremony in Japan.

Joel Ehrendreich is a U.S. Foreign Service Officer currently posted at the embassy in Singapore.

The American Foreign Service Association says when Ehrendreich worked in Tokyo in 2005, he was tasked with formally turning down the ambassador's invitation to the Hiroshima ceremonies.

Hiroshima's mayor had always believed it would be appropriate for the highest-ranking U.S. diplomat to attend. The State Department disagreed.

Ehrendreich said it made no sense to him that the United States should boycott the ceremonies. He spent five years trying to persuade the State Department to change its policy.

Last year, John Roos became the first U.S. ambassador to Japan to go to the Hiroshima ceremony.

The association says Ehrendreich helped strengthen U.S.-Japan relations.

The annual Hiroshima Peace Memorial Ceremony is held every August to mark the anniversary of the United States dropping an atomic bomb on the city in 1945, hastening the end of World War II.