STORY: Nuclear-armed North Korea test-fired an intermediate-range ballistic missile (IRBM) farther than ever before on Tuesday, sending it soaring over Japan for the first time in five years and prompting a warning for residents there to take cover.

South Korean and American troops fired a volley of missiles into the sea in response, South Korea's Joint Chiefs of Staff said on Wednesday, and the allies earlier staged a bombing drill with fighter jets in the Yellow Sea.

The military separately confirmed that a South Korean Hyunmoo-2 missile failed shortly after launch and crashed during the drill, but that no one was hurt.

South Korea's military said that the missile carried a warhead but it did not explode, and apologised for causing residents to worry.