Japan on Thursday urged its citizens in Miyagi, Yamagata and Niigata prefectures to shelter indoors after North Korea launched a ballistic missile off its eastern coast.
The alert came from the Japanese government's emergency early warning system, which confirmed that the North Korean missile had already flown over Japanese territory, heading towards the Pacific Ocean.
The Japanese Prime Minister's Office said in a tweet on Twitter that the missile flew over the country around 7.48 am local time (22.48 GMT Wednesday evening), while television stations cut their programs to urge residents in some areas to take cover or stay in their homes.
For its part, Seoul announced that Pyongyang launched an "unspecified ballistic missile", a day after it also launched more than 20 missiles, one of which landed near the territorial waters of South Korea.
"North Korea fired an unidentified ballistic missile toward the East Sea," the South Korean military's Joint Chiefs of Staff said, referring to the sea, also called the Sea of Japan.
And last Friday, the South Korean military announced that Pyongyang had fired two short-range ballistic missiles toward the Sea of Japan, warning that it was about to conduct a new nuclear test.
The new North Korean missile test and warnings about it come to reminiscent of fears about the arsenal of ballistic missiles and nuclear warheads that Pyongyang possesses and has developed since the 1950s.
Pyongyang does not declare the size of its nuclear warheads or ballistic missiles, and this type of weapon is not included in the statistics of the military strength of countries, which are usually prepared by unofficial bodies.