South Korea's Joint Chiefs of Staff (JCS) said in a statement on 15 September that North Korea had fired what is believed to be two ballistic missiles towards the exclusive economic zone of Japan.
South Korea's JCS noted that it is carefully analyzing the information with US intelligence agencies.
Seoul is also expected to convene its National Security Council over the incident.
Japan's Prime Minister Yoshihide Suga condemned North Korea's launch of ballistic missiles, dubbing the action a threat to peace and security in the region.
Suga also ordered to urgently convene the country's National Security Council.
'North Korea's ballistic missile launches threaten the peace and security of our country and the region.
They are in violation of the UN Security Council's decisions.
We express our strong protest and strongly condemn [them]', Suga said.
Prior to the official statement by the South Korean and Japanese authorities, the nations' media reported about two unidentified projectiles launched within the space of several minutes.