SEOUL - The Republic of Korea (ROK) voiced strong commitment to a tense western sea border with the Democratic People's Republic of Korea (DPRK) in its latest defense white paper released Friday.

"Waters south of the Northern Limit Line (NLL), a de facto maritime border between the ROK and the DPRK, are controlled by the ROK," the report said, referring to the disputed border Pyongyang refuses to acknowledge.

The NLL, drawn unilaterally by the US-led United Nations Command at the end of the 1950-53 Korean War, is a scene of deadly naval skirmishes between the rival Koreas that technically remain enemies to date.

It marks the first time the ROK's defense ministry officially mentions the sea border in its annual report, a move ministry officials said is aimed at better informing the public on the issue.

In the latest conflict surrounding the border, the DPRK shelled a ROK's border island in 2010, which it said was a response to a joint military drill between the ROK and the United States near the NLL.

Pyongyang, which has repeatedly refused to acknowledge the border, refuses to apologize for the attack that killed four South Koreans.