The Pacific Island of Guam raises official threat level

The Pacific Island of Guam has raised its official threat level and has this morning tested its emergency alert system after warnings from North Korea identifying the island as a potential missile target.

A North Korean missile test is expected at any time.

Authorities have said that the US territory is on yellow alert, the middle phase of a three-step "traffic light" system.

A government spokesman described the risk to the island as medium.