Details of the launch were being analyzed by South Korean and U.S. intelligence authorities, South Korea’s Joint Chiefs of Staff said in a statement.
It was the latest in a series of missile tests and military exercises conducted by the North in recent weeks including a failed spy satellite launch late last month.
Seoul announced sanctions on Friday on five North Korean individuals and one company in response to Pyongyang’s launch of what it said was a space rocket last month.
On Thursday state media KCNA reported that Pyongyang had conducted a simulated “scorched-earth” nuclear strike on targets across South Korea, drawing criticism from Seoul.
The joint annual summertime exercises between South Korea and the U.S. known as the Ulchi Freedom Shield came to a close on Thursday after an 11-day run featuring air drills with B-1B bombers. North Korea protested the deployment of the U.S. strategic bombers by firing two ballistic missiles just hours later in retaliation. Pyongyang has long denounced the drills as a rehearsal for war.