Besides firing shots at the North Korean vessel maybe the ROK Coast Guard needs to start firing shots at these illegal Chinese fishing vessels as well:
A South Korean Navy vessel fired warning shots to drive out a North Korean patrol boat that crossed the western de facto maritime border last week, the South’s military said Sunday.
The North Korean boat crossed the Northern Limit Line (NLL) in waters northeast of South Korea’s Baengnyeong Island in the Yellow Sea on Saturday at 11 a.m., prompting the South Korean Navy to dispatch its Chamsuri-class patrol boat, according to the Joint Chiefs of Staff (JCS).
After the North’s boat remained unresponsive to South Korea’s warning broadcasts and communication attempts, the South Korean vessel fired 10 warning shots with its autocannon and made the North Korean boat retreat.
The North Korean boat made the incursion as it was chasing a Chinese fishing boat, according to an informed source.
The JCS said there was contact between the South Korean vessel and the Chinese boat during the operation, and three of the South Korean sailors were sent to a hospital for injuries. One of them is known to have undergone surgery due to a fracture.
Yonhap
You can read more at the link, but this illegal Chinese fishing boat rams a South Korean Coast Guard ship, injures sailors, and it is allowed to get away?