This time, however, the North Korean vessels refused to back off.

He said the South Korean vessel was severely damaged.

Last year, North Korean vessels strayed south of the line 30 times.

"As a result, a Korean naval vessel fired on and sank the submarine."

A North Korean vessel also caught fire and is believed to have been destroyed in the battle.

This time, though, the North Korean vessels held their ground.

The governor had to separate Japanese, Chinese, and Korean vessels to keep the fishing companies running between the islands.

The North Korean vessel then ordered it to stand down or be fired upon.

The North Korean vessels returned to port on 28 March 2010.

Later, several North Korean vessels returned to the area, and the standoff continued.