As part of the drill, a night shift supervisor pretended to be U.S. Pacific Command and played a recorded message that warned emergency workers of an incoming attack. The recording included the phrase “exercise, exercise, exercise.†But it also stated, “This is not a drill,â€Â which apparently prompted the worker to broadcast the ballistic missile alert.Â
Article source: https://www.huffingtonpost.com/entry/hawaii-missile-alert-investigation_us_5a70a256e4b0ae29f08b667d?utm_hp_ref=hawaii