SEOUL, (Yonhap) -- North Korea repeated its claim Saturday that the only maritime border in the western Yellow Sea is the one drawn by Pyongyang, condemning the South Korean president's recent trip to an island near the border where he urged increased efforts to deter any border violation by the communist nation.

South Korean President Lee Myung-bak on Thursday said the country's service members must stake their own lives if necessary to safeguard the Northern Limit Line (NLL), a de facto maritime border drawn by the U.S.-led United Nations Command at the end of the 1950-53 Korean War.

The North mostly refrains from crossing the de facto border, but often claims the NLL, drawn unilaterally by the United Nations Command, is not legitimate and demands a new border be drawn further south of the existing NLL.

"Only the sea military border drawn by us will exist in the Yellow Sea, not the NLL, until unification comes," an unidentified spokesperson for the North's powerful National Defense Commission said in a statement carried Saturday by the communist nation's Korean Central News Agency.

Calling the Yellow Sea border an "ghostlike line," the spokesman said Lee's visit "aimed to hurt our people's peace and stability and pursue war by maintaining the Northern Limit Line, a source of confrontation and conflict."

The Yellow Sea border has been the scene of a number of bloody inter-Korean clashes. The two sides fought naval gun-battles in the area in 1999, 2002 and 2009. In 2010, the North torpedoed a South Korean warship in the area, killing 46 sailors, and shelled Yeonpyeong Island, leaving two South Korean Marines and two civilians dead.

On Friday, a North Korean fishing boat briefly crossed into South Korean waters near the border, but returned after South Korean patrol boats broadcast warning signals. It marked the seventh border violation by the North's vessels in the area since last month.

Meanwhile, South Korea's Defense Minister Kim Kwan-jin said the North "could provoke a war as a means to break through its internal problems," urging the military to take adequate measures in such cases.

His remarks came one day after Pyongyang threatened to launch military attacks on a South Korean border area if Seoul allows anti-North activists to send propaganda leaflets into the communist nation next week as planned.

"If the enemy provokes a war, make a counterattack regardless of how many rounds of shells you fire," Kim said during his visit to the front-line troops in Gangwon Province in the day.

Citing a series of North Korean soldiers' defection to the South, Kim said, "It serves as evidence that the North's worsening economic difficulties and food shortages in the course of its power succession are even affecting its military."

Although defection via land border has been considered rare, a total of three North Korean soldiers crossed the border for defection this year alone.