North Korea fired at least one unidentified ballistic missile Monday, South Korea's military said, the latest in its flurry of weapons tests in recent weeks.
"North Korea fires an unidentified ballistic missile towards the East Sea," Seoul's Joint Chiefs of Staff said, referring to the body of water also known as the Sea of Japan.
Japan's defence ministry also said "a suspected ballistic missile has been fired", with its coast guard saying the weapon was believed to have already fallen.
The launch comes as Seoul and Washington are carrying out a joint amphibious landing exercise, just days after wrapping up their largest combined military drills in five years Thursday.
Pyongyang views all such exercises as rehearsals for invasion and on Friday claimed the recent drills, dubbed Freedom Shield, were practice for "occupying" North Korea.
Pyongyang carried out military drills of its own in response, including test-firing a new nuclear-capable underwater drone and conducting its second intercontinental ballistic missile launch this year.
Analysts previously said North Korea would likely use the drills as an excuse to carry out more missile launches and perhaps even a nuclear test
North Korea's state media said Friday the "underwater nuclear attack drone" drill, which was personally overseen by leader Kim Jong Un, was staged "to alert the enemy to an actual nuclear crisis."
The weapon's mission is to "stealthily infiltrate into operational waters and make a super-scale radioactive tsunami ... to destroy naval striker groups and major operational ports of the enemy," the Korean Central News Agency reported.
The agency also said Pyongyang had fired strategic cruise missiles "tipped with a test warhead simulating a nuclear warhead" on Wednesday.
Analysts questioned North Korea's claims, saying that they were not the same as a credible demonstration of capability.
But they added that Pyongyang was moving on from simply stockpiling nuclear warheads and attempting to advance and diversify launch mediums.
After a record-breaking year of weapons tests and growing nuclear threats from Pyongyang in 2022, Seoul and Washington have ramped up security cooperation.
It has also pushed South Korea and Japan to mend fences over historical disputes and try to boost security cooperation.
North Korea last year declared itself an "irreversible" nuclear power and Kim recently called for an "exponential" increase in weapons production, including tactical nuclear weapons.
Kim also ordered the North Korean military this month to intensify drills to prepare for a "real war."