South Korea's Joint Chiefs of Staff (JCS) said that North Korea fired one unidentified ballistic missile toward the East Sea at around 7 a.m. Sunday.
The military is analyzing the details of the launch, including the range, altitude and speed.
The missile was reportedly launched from an inland area in North Korea.
The South Korean military recently said it detected signs suggesting the North may be preparing to fire a submarine-launched ballistic missile (SLBM) from the Sinpo area on the east coast.
The latest launch marks the North's fifth missile firing since the launch of the Yoon Suk Yeol administration in May. North Korea last fired eight short range ballistic missiles on June 5.
The firing comes after the USS Ronald Reagan carrier strike group arrived in the southern port city of Busan on Friday to hold combined drills with the South Korean Navy.