North Korea fired a ballistic missile from South Pyongan Province at dawn, Yonhap News Agency reported, citing the South Korean military.
The United States and South Korea are studying the missile's trajectory. It was earlier reported that North Korea could launch a missile in a few days' time.
Pyongyang last tested a missile Sept. 15.
The missile landed within Japan's exclusive economic zone, which covers large swaths of ocean around Japan, NBC News reported separately. Officials from South Korea and the U.S. did not confirm the missile landing area.
Reports of the launch caused U.S. equity markets to pause their upward trajectory on a day when the major averages were headed for new record highs. The S&P 500 had been as high as 2,621.31 just after 1:00 p.m. ET, before the news of North Korea's action. The average touched 2,610 at around 2:00 p.m. ET, about 30 minutes after the first reports of the launch, but recovered to just over 2,619 by 2:40 PM. The yield on 10-year U.S. Treasury notes was essentially flat at 2.33% at 2:40 p.m. ET, after trading above that level for much of the day.