NEW YORK (NYTIMES) - As tensions between the United States and North Korea continue to simmer, Hawaii is preparing to resume a statewide test on Friday (Dec 1) 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 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 Wednesday, its latest action that raises the stakes in an increasingly tense standoff with the United States.

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," Miyagi said.

The last time Hawaii residents heard the attack warning siren test was in the mid-1990s, after the waning of the Cold War.

"We stopped using it in the mid-1990s after the Cold War ended in the '80s," said Richard Rapoza, the spokesman for the emergency management agency, in a telephone interview Tuesday.

"At that point, there was no longer a need for it. Somebody finally decided we don't need this anymore. It was not really serving a purpose."

Rapoza said state authorities thought a missile attack was "extremely unlikely," but they were holding frequent town hall meetings to reacquaint people with the important role of the siren.

"It is our job to prepare people for any kind of emergency," he said. "So now because of the North Korea threat, we are starting to use it again."

The siren, if used as an actual warning, would signal to people that they should immediately seek shelter, Toby Clairmont, the executive officer of the emergency agency, said in a report by the Honolulu Star-Advertiser this month.

In July, after North Korea tested an intercontinental ballistic missile that appeared capable of hitting America's two most western states - Alaska and Hawaii - Hawaii's emergency management authorities released guidelines on how to survive a nuclear detonation, offering advice to seek shelter in a blast-resistant structure within minutes.

Friday's test of the siren in Hawaii also comes amid reports that North Korea has been conducting missile engine and fuel tests in recent weeks, with the goal of achieving nuclear-tipped intercontinental ballistic missile capabilities as early as next year, South Korea's lead official on the North, Unification Minister Cho Myoung-gyon, said Tuesday.

North Korea claimed to have detonated a hydrogen bomb Sept 3, in its sixth and most powerful nuclear test yet.