Part of the coast in Oahu. Hawaii is testing a nuclear warning siren that will alert people to seek shelter in the face of an imminent attack.

Jim Wilson/The New York Times

As tensions between the United States and North Korea continue to simmer, Hawaii will start 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.”

For several weeks, the authorities in Hawaii have been discussing their plans to sound the Attack Warning Tone. On Nov. 8, Hawaii’s emergency management agency released a public service announcement featuring its administrator, Vern Miyagi, speaking on the importance of the tone while ukulele music played lightly in the background.

“The attack warning signal advises everyone to take immediate shelter — get inside, stay inside, stay tuned,” Mr. Miyagi said.

HI-EMA Emergency Preparedness PSA 3 Video by Hawaii DOD Public…

…rest of the post