Senior generals from North and South Korea have held the first of three days of talks aimed at easing border tensions on the divided peninsula.
N Korean officers last met their S Korean counterparts in May
North Korea renewed its demand for the long-running dispute over the western sea border to be addressed.
Negotiations have failed in the past because North Korea wants the sea border to be redrawn further south.
The talks come amid improving ties, with the North finally shutting down its Yongbyon nuclear reactor last week.
The closure was part of an international disarmament deal under which North Korea receives energy aid and political incentives in return for ending its nuclear programme.
The talks between the generals are the highest-level military dialogue between the two Koreas, who have not signed a peace treaty since the Korean War and remain technically at war.
The western sea border has been a long-running dispute between the two sides.
Pyongyang does not recognise the border line - known as the Northern Limit Line - drawn up by the UN at the end of the 1950-53 war.
This has resulted in a number of naval clashes in the disputed rich fishing waters. Six South Korean sailors were killed in one clash in June 2002.
North Korea also accuses South Korean vessels of regularly violating its territorial waters - something Seoul denies.
Following Tuesday's opening meeting, Col Moon Seong-mook of the South Korean military said: "Of course there was a mention of the Northern Limit Line.
"The North said the issue needs to be discussed. We stressed again that our position... is firm."
He said the atmosphere of the first day of talks was "not bad", even though they concluded earlier than planned.
As well as looking at the sea border, the talks are also due to focus on security arrangements for joint economic projects.