More North Korean fishing vessels have crossed the Northern Limit Line (NLL) inter-Korean maritime border since the sinking of the Cheonan.

Joint Chiefs of Staffs (JCS) spokesman Col. Park Sung-woo told reporters that North Korean fishing boats have crossed the NLL into South Korean waters some 20 times this year. He said the occurrences have been notably frequent since the Cheonan incident.

The spokesman added that although it had confirmed that the North Korean military operates fishing vessels on the coast for additional income, no on-board heavy artillery has been confirmed.

Although Col. Park said the North Korean fishing boats returned to North Korean waters without protest after South Korean warnings, he says the JCS is closely monitoring the boats to see if the crossings were intentional.

The JCS views the appearance of North Korean military officers at the Demilitarized Zone and their observation of South Korean territory as routine.