North Korea fired an unidentified projectile on Monday (local time) from the region of Wonsan on its east coast in an easterly direction, South Korea's military said, according to Reuters.
The launch was immediately reported to President Moon Jae-in, who called a meeting of the National Security Council at 7:30 a.m., the South Korean office of the Joint Chiefs of Staff said in a statement.
The projectile was likely a ballistic missile, South Korea's Yonhap news agency said, citing an unidentified source.
A spokesman for the Japanese government said the missile launched landed in the Sea of Japan.
The incident comes just one day after North Korean state media reported that leader Kim Jong-Un had overseen a test of a new anti-aircraft weapon system.
Just last week, North Korea test-fired a medium-range ballistic missile , which it claimed was also supervised by Kim.
The West is concerned that North Korea may be on a path to developing an intercontinental ballistic missile (ICBM).
North Korea has declared that it could test-launch an ICBM “at any time” from any location set by its leader Kim Jong Un, though it remains unclear whether any of its recent tests have been of an ICBM.