North Korea’s Navy claims South Korean ships have often trespassed into its waters, creating a mood for a possible naval clash in the Yellow Sea.

The North’s Navy Command said in a statement Thursday that it will deal sternly with any violations of its sovereignty.

The statement said there is a limit to the North’s patience, adding that the South needs to deeply contemplate the consequence of its actions.

The statement added that it will not tolerate the Lee Myung-bak government’s policy on seeking to maintain the Northern Limit Line (NLL).

In late March, the North Korean Navy called the NLL a "ghost line," and warned that it would not sit and watch perceived reckless provocations by South Korean warships in its waters.

In April, the North’s Navy warned that it would act accordingly if the South continues to infiltrate into North Korean waters.

The NLL is a de facto maritime border in the West sea drawn by the United Nations forces at the end of Korean War in 1953, but North Korea never officially recognized the border. It has been a source of military tension between the two Koreas since then, especially during the fishing season.