North Korea early Monday test-fired a ballistic missile, according to South Korea's military as Seoul officials swiftly responded by convening a national security meeting.
The suspected Scud-type missile was launched at 5:39 a.m. (0839GMT Sunday) from the eastern Wonsan area before flying around 450 km and landing in open waters, the South's Joint Chiefs of Staff (JCS) said.
It marks the North's third ballistic missile test in less than three weeks since South Korean President Moon Jae-in took office, despite high hopes for Seoul-Pyongyang ties under the new administration.
It is the reclusive state's ninth launch this year, involving projectiles of various ranges.
"Our military is keeping a close watch on the possibility of an additional provocation by North Korea and is maintaining full preparedness," the JCS stated.
Pyongyang is barred from testing ballistic missiles under multiple United Nations Security Council resolutions.
However, the North insists it has a sovereign right to defend itself against the regional deployment of American troops and military hardware.
North Korea's state-run media celebrated Sunday the successful development of a new anti-aircraft weapon system, which ruler Kim Jong-un said would “completely spoil the enemy’s wild dream to command the air”.