South Korean Defense Minister Kim Jang-soo said Friday that the Northern Limit Line, or NLL, will remain the de facto West Sea border with North Korea.

He told a news briefing that while the NLL issue was not on this week's inter-Korean summit agenda, President Roh Moo-hyun explained to North Korean leader Kim Jong-il about South Koreans' perception of the sea border.

According to the defense minister, the North Korean leader said he understood and made no further comment about it.

The minister noted that although the two Koreas have not reached agreement on the location of a joint fishing area, it should be set up around the NLL.

He added that its location should be discussed during the upcoming inter-Korean defense ministers' talks.

The defense chief also said that while Seoul's rules of engagement in the prospective joint fishing area will remain valid, the two Koreas should prevent warships from entering the fishing zone.

Asked if the South Korean Navy will change its operational concept after a peace zone is set up on the Yellow Sea, the minister said he thinks the two Koreas need a separate agreement on the issue.