Operation Ivy, Mike Explosion “The island of Elugelab is missing!” President Truman heard this short report from Gordon Dean, chairman of the Atomic Energy Commission, following the “Mike shot,” conducted as part of Operation Ivy. Mike, which delivered 10.4 megatons, was the first full-fledged hydrogen bomb to be detonated. It vaporized the small islet of Elugelab in the Eniwetok Atoll.