FILE - In this July 25, 1946 file photo, a huge mushroom cloud rises above Bikini atoll in the Marshall Islands following an atomic test blast, part of the U.S. military's "Operation Crossroads." Bikini Atoll in the Marshall Islands remains contaminated by radiation, part of a troubling nuclear testing legacy that continues to affect islands and people across the Pacific long after the U.S., Britain and France stopped their testing programs there. (AP Photo, File)