Making only the second trip ever by a serving prime minister to the site of the Battle of Iwojima, Naoto Kan paid his respects Tuesday to the more than 21,000 Japanese soldiers killed in one of World War II's bloodiest battlegrounds — and one that after 65 years is still giving up its dead.

Kan's visit followed the recent discovery of two mass graves on the tiny, volcanic isle where the remains of roughly 12,000 Japanese soldiers have yet to be recovered. Officials traveling with Kan said the visit underscores his resolve to finally account for all of Iwojima's dead.

"We will examine every grain of sand," Kan said, offering a prayer at one of the two mass graves. "It is hard to imagine from the beauty of the island today what happened here 65 years ago."