The South Korean military was monitoring the relevant situations and maintaining readiness posture to prepare for a possible additional launch, the JCS said. 

South Korean President Moon Jae-in was to convene a National Security Council (NSC) meeting after the projectile launch.

President Moon condemned the launch as a challenge to international efforts to ensure peace and stability on the Korean Peninsula and urged North Korea to stop creating tension and respond to international calls for dialogue.

Meanwhile, Japan's top government spokesman said the missile appears to have splashed down outside the country's exclusive economic zone, and that there was no immediate report of damage to ships or aircraft in the area. 

The missile may have been medium- or long-range, Japanese Chief Cabinet Secretary Hirokazu Matsuno said, suggesting the missile could reach the entire Japanese archipelago and the US territory of Guam in the western Pacific.

Sunday’s launch is believed to be the 7th missile launch by North Korea this month alone.