The state Thursday released an audio recording of the drill it was running in January when an employee mistakenly sent cellphone and broadcast alerts warning of a ballistic missile attack.

But the 24-second recording the Hawaii Emergency Management Agency released was heavily redacted.

It started with the words “exercise, exercise, exercise,” followed by a prolonged beep, then the phrase “this is not a drill” and another prolonged beep. It ended with “exercise, exercise, exercise.”

Spokesman Lt. Col. Charles Anthony said the agency could only disclose a small portion of the recording because the U.S. Pacific Command would use the same or similar language if it notified the agency of an actual missile threat.

“Somebody could use that verbiage to compose a message, then call the state warning point and try to spoof state warning point into thinking there was a real missile alert,” Anthony said.

He said this could be a prankster, North Korea or “something in between.”

The recording isn’t classified, but the material is so sensitive that the emergency management agency treats it like it is, Anthony said.

But Brian Black, executive director of the Civil Beat Law Center for the Public Interest, said it’s troubling that the agency is releasing only portions that support its narrative of what happened.

The employee who sent the alert has said he didn’t hear the word “exercise” spoken during the drill and thought the threat was real. The agency has since fired him.