South Korea's Navy fired shots after a shell presumably fired by the Democratic People's Republic of Korea (DPRK) fell near disputed western sea border, the Joint Chiefs of Staff (JCS) said Wednesday.

The Navy heard the sound of shelling and fired three shots in response, and later confirmed one of the DPRK shells landed near the sea border the DPRK does not acknowledge.

South Korea is keeping tabs on the DPRK, which might have been engaged in routine drills, according to the JCS.

The DPRK shelled a South Korean island near the disputed sea border last November, killing four South Koreans. Pyongyang said the incident was provoked by a drill of Seoul.