Hawaii has conducted its first test of a siren to warn the public of a possible nuclear attack from North Korea.

The US state is the first to test a Cold War era nuclear warning system since the end of the Cold War.

The siren sounded for a minute on Friday after the usual testing of a system to alert people to natural disasters.

The move comes in the same week North Korea fired a powerful nuclear-capable intercontinental ballistic missile that some observers believe could reach the US mainland.

Hawaii governor David Ige said the possibility of a strike is remote but that people have to be prepared.

Officials delayed testing by a month to ensure residents and visitors were informed.

Some still expressed confusion this week about what they were supposed to do after hearing the attack siren.