South Korea's military says North Korea fired a ballistic from its capital Pyongyang toward the sea between the Korean Peninsula and Japan.
Seoul's Joint Chiefs of Staff on Tuesday said the South Korean and U.S. militaries were analyzing the launch and didn't immediately confirm how far the projectile traveled and where it landed.
A former South Korean military official who is now an analyst at Seoul's Institute for Far Eastern Studies said that the early flight data suggests the North Korean missile that flew over Japan was likely a Hwasong-12, a new intermediate range missile that the North has recently threatened to fire toward Guam.
The U.S. Defense Department said it is in the process of assessing the launch.
Japanese officials said there was no damage to ships or anything else reported. Japan's NHK TV said the missile separated into three parts.
Analyst Kim Dong-yub a said there was also a possibility the missile could have been a midrange Musudan, a missile with a potential 3,500-kilometer (2,180-mile) range that puts much of the Asia-Pacific region within reach, or a Pukguksong-2, a solid-fuel missile that can be fired faster and more secretly than weapons using liquid fuel.
The launch comes days after the North fired what was assessed as three short-range ballistic missiles into the sea and a month after its second flight test of an intercontinental ballistic missile, which analysts say could reach deep into the U.S. mainland when perfected.
The North has also threatened to lob some of its missiles toward Guam and expressed anger over the ongoing annual war games between the United States and South Korea.