Atomic bomb test, Kiritimati, 1962. The US conducted a series of 31 atom bomb tests in 1962 under the codename Operation Dominic. This mushroom cloud is from one of the 24 tests carried out at Kiritimati (Christmas Island) in the central Pacific Ocean. These tests were carried out between April and July of that year. These tests were among the last atmospheric tests carried out by the USA, with the Limited Test Ban Treaty being ratified in 1963.