The United States nuclear program since its inception has experienced accidents of varying forms, ranging from single-casualty research experiments (such as that of Louis Slotin during the Manhattan Project), to the nuclear fallout dispersion of the Castle Bravo shot in 1954, to accidents such as crashes of aircraft carrying nuclear weapons, the dropping of nuclear weapons from aircraft, losses of nuclear submarines, and explosions of nuclear-tipped missiles (broken arrows). How close any of these accidents came to being major nuclear disasters is a matter of technical and scholarly debate and interpretation.