“The [Republic of Korea] ROK military detected two short-range ballistic missiles fired from North Korea’s Sunan area in Pyongyang into the East Sea from 6.10 to 6.20pm,” South Korea’s Joint Chiefs of Staff (JCS) said, according to the Seoul-based website NK News.
It added that the country’s military has “strengthened surveillance and security and is maintaining a full readiness posture in close coordination with the US”.
It is not immediately clear the range and altitude of the missiles tested.
An earlier update by South Korea’s JCS had referred to one “unidentified ballistic missile” fired towards the East Sea. This was later updated to say two projectiles had been launched.
The office of Japan’s prime minister Fumio Kishida also said that a projectile had been launched by North Korea and that it was a suspected ballistic missile.
Mr Kishida ordered officials to take precautionary measures and ensure the safety of aircraft and ships in response to the missile launch. “Dedicate maximum effort to gather and analyse information, and provide the public speedy and adequate information,” read the instructions issued by the prime minister’s office.
The firing of the missiles comes on the eve of US vice president Kamala Harris’s visit to Seoul on Thursday.
Ms Harris will be visiting the Demilitarised Zone (DMZ) separating North and South Korea on Thursday, becoming the latest top US official to visit the peninsula.
These are likely to be the second and third ballistic missiles fired by Pyongyang off its east coast in less than four days, at a time when North Korea’s rival South Korea and the US are carrying out drills in the region.
Earlier this week, the US and South Korea began their first major joint drills off the Korean peninsula’s east coast in five years.
The drills, spanning over four days, are aimed at demonstrating the allies’ “powerful resolve to respond to North Korean provocations” and improve their ability to perform joint naval operations, the South Korean navy said in a statement.
Sunday’s missile launch saw a projectile fired from North Korea reach an altitude of 50km, Japan said. Tokyo added that the missile landed outside its exclusive economic zone.
Last week, analysts predicted North Korea was preparing to fire submarine-launched ballistic missiles, after satellite images confirmed activities were underway in its port city Sinpo.
The tests were predicted to take place this week on Wednesday and Thursday in North Korea’s South Hamgyong province, sparking concerns of another missile test in the next 24 hours.
Intelligence from US-based think tanks also said that the isolated country could be preparing to carry out a submarine-launched ballistic missile test.
New satellite images taken on 18 September have confirmed infrastructure at the Sinpo South Shipyard on the Korean country’s east coast.
At least six news barges and vessels were detected around the submarine construction hall which was not previously present, according to 38 North, a programme of the nonpartisan Stimson Centre think tank which monitors North Korea.