Clarification of Johnston Island Nuclear Tests

US nuclear weapons launched from Johnston Island for testing purposes in 1958 and 1962 resulted in 12 successful launches, from which high-altitude nuclear detonations occurred, and four failed launches, resulting in aborted tests with no nuclear detonations. Lists of US nuclear tests produced by testing organizations include only events in which nuclear detonations occurred. Hence, the four failed launches in which no nuclear detonation occurred were not considered tests and are not in the lists, even though three of the failed launches resulted in significant local contamination of Johnston Island. A few summaries of nuclear testing at Johnston Island have mistakenly assumed that the launches resulting in local contamination were among the 12 nuclear tests listed for Johnston Island. This note explicitly lists the identities of all 16 launches of nuclear devices from Johnston Island for the purpose of correcting this assumption.