Guam has raised its official threat level and on Thursday tested its emergency alert system after warnings from North Korea identifying the island as a potential missile target.
With a North Korean missile test expected at any time, authorities said the US territory in the western Pacific was on yellow alert, the middle phase of a three-step "traffic light" system comprising green, yellow and red levels.
"This means we should continue with our daily lives while preparing ourselves for any potential of an emergency," the government said in a statement, describing the risk to the island as "medium".
"It also means the government pulls its resources together through the emergency operations centre to ensure we are prepared to respond to emergencies."
Guam's emergency alert system, which sets off sirens across the island and interrupts regular television and radio broadcasts to deliver information, was tested at 10:00 am (0000 GMT) Thursday.
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