The South Korean military said North Korea conducted a short-range ballistic missile launch toward the Yellow Sea, off the western coast of the Korean Peninsula. It said several missiles may have been fired simultaneously.
South Korea's Joint Chiefs of Staff said the launch was carried out at or near the western North Korean city of Nampho at around 6:20 p.m. on Thursday.
The launch comes at a time when the United States and South Korea are preparing to start large-scale joint military drills on March 13.
On Tuesday, Kim Yo Jong, the sister of North Korean leader Kim Jong Un, said in a statement that the North is "always on standby to take appropriate, quick and overwhelming action at any time."