North Korea has claimed that it detonated explosives that successfully deceived South Korea into believing that an artillery drill was conducted.

In a statement published by the state-run Korean Central News Agency on Sunday, Kim Yo-jong, the powerful sister of the North’s leader Kim Jong-un, said that the Korean People’s Army detonated explosive powder simulating the sound of its coastal artillery in a test of the South Korean military’s detection abilities.

Kim said that as expected, the South’s military misjudged the sound as artillery fire and incorrectly concluded that it was a provocation, even claiming falsely that shells fell into the buffer zone north of the Northern Limit Line.

Kim then warned that the North will launch an immediate military strike if the South makes even a slight provocation.

South Korea’s Joint Chiefs of Staff(JCS) dismissed Kim’s statement as rudimentary psychological warfare, urging the North to cease military activity that raises tensions near the maritime border. 

The JCS said that the military's detection assets also picked up North Korea's artillery firing on Saturday, saying that some 60 shells were fired into waters north of the western sea boundary for an hour from 4 p.m. near South Korea’s Yeonpyeong Island.

The South Korean military did not conduct firing exercises to respond to the North’s drills after determining that the direction of North Korean shells fired Saturday was less provocative than Friday.