FILE - In this April 16, 1944, file photo, a combined force of American and Royal New Zealand Air Force dive bombers taxi to a runway on the island of Bougainville in Papua New Guinea. The island is where American fighters shot down Admiral Isoroku Yamamoto, the mastermind of the Pearl Harbor attack, making the wreck site one of most important of World War II. Now, 75 years later, a group from the U.S. and Japan is trekking to the remote Pacific island to document the site. (AP Photo/Frank Filan, File)