North Korea says that multiple artillery shells it fired toward a buffer zone in the Yellow Sea on Monday were warning shots, accusing a South Korean warship of crossing the military demarcation line(MDL).

Pyongyang’s official Korean Central News Agency(KCNA) on Monday carried the claim by the General Staff of the Korean People’s Army that a South Korean escort ship made an incursion of two-point-five to five kilometers across the MDL into waters controlled by the North’s military at 3:50 a.m.

The North Korean military asserted that the “intrusion” by the South was carried out on the pretext of cracking down on an unidentified vessel, adding that ten artillery shells were fired as an initial countermeasure.

The regime’s arguments came as the South’s Joint Chiefs of Staff detected earlier in the day that the artillery shots were fired from around Jangsan Cape, South Hwanghae Province from 5:14 a.m. into the buffer zone north of the Northern Limit Line(NLL).

Earlier in the day, a North Korean merchant ship crossed the NLL, the de facto maritime border between the two Koreas, before retreating after the South Korean military fired warning shots.