Missile thought to have likely exploded while lifting off from a mobile launcher
North Korea has failed to launch its Musudan missile for the fourth time, South Korea claims.
The Yonhap News Agency said the North attempted to test fire the intermediate-range weapon from its east coast in the early hours.
Both South Korea and the US reported three such failures in April.
A South Korean government source told the agency the missile was likely to have exploded while lifting off from a mobile launcher.
North Korea is thought to have up to 30 Musudan missiles, which could reach as far as US military bases in Asia and the Pacific.
Tension is high in the region after North Korea conducted its fourth nuclear test in January, followed by a satellite launch.
Japan put its military on alert on Monday for a possible North Korean ballistic missile launch.
"We have no reports of any damage in Japan. We are gathering and analysing data. The defence ministry is prepared to respond to any situation," Japanese Minister of Defence Gen Nakatani told reporters.
"North Korea shows no sign of abandoning the development of nuclear missiles and so we will continue to work closely with the US and South Korea in response and maintain a close watch on North Korea."
Earlier this month, Kim Jong-Un further consolidated his control at the first congress in 36 years of North Korea's ruling Workers' Party.