North Korea fired an unidentified ballistic missile toward east sea that has since been reported to have flown over Japan.

Nevertheless, Japan warns residents to take shelter in the threat of the North Korean missile.

Meanwhile, the BBC reported that the North launched its most missiles in a single day - at least 23 - including one that landed less than 60km (37 miles) off the South's city of Sokcho.

''Seoul responded with warplanes firing three air-to-ground missiles over the disputed maritime demarcation line.

Later Pyongyang fired six more missiles and a barrage of 100 artillery shells.

The North says the launches are in response to large-scale military exercises current being held by South Korea and the United States, which it calls "aggressive and provocative".

On Tuesday, Pyongyang warned they would pay "the most horrible price in history" if they continued their joint military drills, seen as a veiled threat to use nuclear weapons.

US secretary of state, Antony Blinken, and his South Korean counterpart, Park Jin, condemned North Korea's "escalatory launch of ballistic missiles".

The North has tested a record number of missiles this year as tensions have risen.''

The BBC has also warned that despite crippling sanctions, Pyongyang has conducted six nuclear tests between 2006 and 2017, and is rumoured to be planning a seventh. ''It has continued to advance its military capability - in breach of United Nations Security Council resolutions - to threaten its neighbours and potentially even bring the US mainland within striking range.''