Several concerned listeners were reported to have called police after the stations triggered the Emergency Alert Broadcast System.
Several concerned listeners were reported to have called police after the stations triggered the Emergency Alert Broadcast System, issuing "a civil danger" warning at 12:25 am that was later confirmed to be a mistake.
North Korea had said it would finalise plans by mid-August on whether to fire missiles at Guam in response to "fire and fury" threats from US President Donald Trump.
But Pyongyang's official Korean Central News Agency (KCNA) on Tuesday reported that Kim had examined the plans but made no move towards an immediate strike.
"Residents and visitors are reminded to remain calm," said Guam’s homeland security adviser George Charfauros.
"There is no change in threat level, we continue business as usual."
Homeland Security confirmed in a statement that the "unauthorised test was not connected to any emergency, threat or warning" and it was working with the radio stations "to ensure the human error will not occur again".
Kim on Tuesday hinted he would hold off on the missile strike, saying he would "watch a little more the foolish and stupid conduct of the Yankees spending a hard time of every minute of their miserable lot".