Residents of South Korea’s capital city Seoul woke to the sound of an air raid siren and an evacuation message played over loud speakers.
The warning was a false alarm, prompted by a failed attempt by North Korea at launching a spy satellite into space, that ended up crashing into the sea.
Earlier Pyongyang had announced plans to launch a satellite to monitor US military activities by 11 June.
Residents of Okinawa in the south of Japan were also issued a warning in response to the launch.