The South Korean military said two North Korean patrol boats crossed the western maritime border and retreated early Friday morning.
 
An official at the Joints Chiefs of Staff (JCS) said the two fishing inspection vessels crossed Northern Limit Line (NLL) maritime border in the Yellow Sea at 4:35 a.m. and came one-point-eight kilometers south of the border in waters east of Socheong Island.
 
The North Korean vessels retreated at 5:03 a.m after the South Korean Navy broadcast several warnings and fired warning shots.
 
The JCS official said the vessels may have crossed the NLL in an attempt to crack down on Chinese fishing boats in nearby waters. The official added it is also possible the North was testing South Korea’s military vigilance.