Castle Bravo was the code name given to the first U.S. test of a dry fuel thermonuclear hydrogen bomb device, detonated on March 1, 1954, at Bikini Atoll, Marshall Islands, by the United States, as the first test of Operation Castle (a longer series of tests of various devices). Fallout from the detonation intended to be a secret test — poisoned the islanders who inhabited the test site, as well as the crew of Daigo Fukuryū Maru (Lucky Dragon No. 5), a Japanese fishing boat, and created international concern about atmospheric thermonuclear testing.