North Korea fired two unidentified projectiles from the eastern coastal city of Wonsan on Monday, South Korea's defence ministry said.
"The military is monitoring for additional launches and maintaining readiness," said South Korea's Joint Chiefs of Staff.
They were unable to confirm how far the projectiles flew or whether it was ballistic or rocket artillery.
The launches come just days after North Korea's Kim Jong-Un oversaw military drills.


Iran threatens painful response if US renews attacks
Ukrainian drones hit Russian port of Tuapse for the fourth time
Detained Myanmar ex-leader Suu Kyi to meet legal team this weekend
UK police charge man over stabbing attack in London
