The discussions were scheduled for Thursday at Panmunjom, a North Korean border village, after Pyongyang agreed to Seoul's proposed date for the working-level military meeting.
North Korea originally proposed Sep 15 for the meeting and said it wanted to discuss border questions, including critical leaflets sent across the border by South Korean activists and ways of preventing naval clashes in the Yellow Sea.
South Korea proposed discussing ways of reducing tensions along the maritime border and the sinking of one of its warships in March with the loss of 46 lives. Seoul has blamed Pyongyang for the sinking, a charge it denied.
The torpedoing of the corvette Cheonan inflamed tensions on the Korean Peninsula.
There have been signs of improving relations with the release of a South Korean fishing boat and the North's proposal of fresh reunions of families separated by the 1950-53 Korean War and division of the Korean Peninsula.
Yonhap said that the South Korean military was wary of the provocative actions by the North, followed by talks aimed at winning concessions.