Honolulu city leaders and their counterparts from Hiroshima, Japan, commemorated the 60th anniversary of the sister-city relationship between the two municipalities by renewing the partnership at a ceremony Tuesday.

Honolulu Mayor Kirk Caldwell and Council Chairman Ikaika Anderson signed the agreement with Hiroshima Mayor Kazumi Matsui and Council Chairman Haruo Yamada at Honolulu Hale.

Matsui was one of a handful of Japanese mayors who took part in the recent 87th annual U.S. Conference of Mayors meeting hosted by Caldwell.

Hiroshima became Honolulu’s first sister city under a Honolulu Board of Supervisors resolution adopted in 1959 and signed by then-Mayor Neal Blaisdell. The agreement was also the first sister-city partnership for Hiroshima.

During Tuesday’s ceremony, Caldwell noted that the fighting between the United States and Japan in World War II began with the Japanese bombing of Pearl Harbor in 1941 and ended with the U.S. bombing of Hiroshima in 1945.

The partnership “is a living and breathing symbol, a funnel through which our shared history of conflict and peace between our two great countries, the United States and Japan, is told repeatedly all the time here,” Caldwell said. “It is a dream about world peace in a time of great conflict.”

“Both of our cities experienced definitive tragedies,” Matsui said. “I believe these strategies are what brought our cities together” to foster peace, friendship and goodwill.”

About one-third of the roughly 30,000 people who immigrated to Hawaii from Japan between 1885 and 1894 originated from Hiroshima.

After Tuesday’s signing, the delegates planted a sapling at Foster Botanical Garden that was raised from the seed of a tree that survived the 1945 atomic bombing of Hiroshima. The planting is part of a Hiroshima program that sends seeds from trees that survived the bombing, called moku or hibakujumoku, to locations throughout the world.