North Korea fired at least one short-range ballistic missile toward the East Sea on Thursday, South Korea's military said.

The Joint Chiefs of Staff (JCS) said the missile was launched from the eastern coastal Wonsan area in the North at around 5 p.m.

The number of missiles launched was not immediately known.

"While strengthening monitoring and surveillance against potential additional launches, our military is maintaining a full readiness posture and closely sharing relevant information with the United States and Japan," the JCS said.

The latest launch comes over a month after North Korea last conducted the test of a tactical ballistic missile as well as new multiple rocket launchers and other weapons on June 25, overseen by North Korean leader Kim Jong-un.

The North's weapons tests coincided with the 76th anniversary of the outbreak of the 1950-53 Korean War, in an apparent bid to demonstrate its ability to target major facilities in the South.