As tensions between the United States and North Korea continue to simmer, Hawaii is preparing to resume a statewide test on Friday of a Cold War-era early warning system designed to inform its residents of an impending nuclear attack.

The Attack Warning Tone, described as a “wailing tone,” will be heard for about 50 seconds on the first business day of every month, beginning on Dec. 1. It will sound after the regular monthly test of the sirens that warn residents of hurricanes or tsunamis, the Emergency Management Agency said in a news release on Monday that was intended to update the population on what the agency is doing to “prepare our state for a nuclear threat.”

Hawaii’s announcement this week of the start of the regular testing of the siren is the latest step the state has taken to prepare its population of more than 1.4 million people for the possibility of a North Korean nuclear strike, even though authorities there say one is unlikely.

It came before North Korea fired a ballistic missile at dawn on Wednesday, its latest action that raises the stakes in an increasingly tense standoff with the United States.