Seoul (CNN) -- Talks between North and South Korea collapsed Wednesday after the two sides failed to reach an agreement on securing high-level military discussions during preparatory meetings held in the border area of Panmunjom.

The resumption of talks, the first of its kind since the Yeonpyeong island bombing that killed four South Koreans last November, signaled a change in atmosphere between the two Koreas. It led many to speculate that a consensus on holding higher-level military would be reached.

However, the North Korean delegation walked away from the negotiating table less than five hours after the second round of talks had begun, a move that was called "unilateral" by the South Korean Defense Ministry.

One of the issues that stalled talks was North Korea's demand for a comprehensive agenda from both sides on possible military actions, while the South pushed to limit the talks to the sinking of the Cheonan warship and Yeonpyeong Island attack, the South Korean Defense Ministry said.

The South and North ran into a similar deadlock while discussing the agenda of the high-level talks on the first day Tuesday. Seoul has demanded that North Korea apologizes for its military provocations carried out last year that also include the sinking of a warship that killed 46 sailors in March.

Pyongyang has denied involvement in the case.

South Korea emphasized Tuesday that it wants the agenda of the high-level talks to specify the island bombing and warship attack. The North argued back, saying that restricting the talks to those issues is "the equivalent of refusing to hold higher-level military talks," according to Seoul's Defense Ministry.

The resumption of humanitarian talks may also be in jeopardy because of the collapse in military talks.

Seoul earlier in the day sent a message to the North saying that it agreed in principal to hold humanitarian talks, in response to two requests Pyongyang had made this year, according to the Unification Ministry.

The South said it would be willing to discuss the details of the time and venue of the humanitarian talks after the high-level military talks are over. The Unification Ministry has not yet indicated whether the collapse of the military talks will push back or affect the resumption of the so-called Red Cross talks.

The Red Cross talks are used to facilitate reunions for families separated by the Korean War and for the North to receive humanitarian aid such as rice and fertilizer from Seoul.

CNN's Paula Hancocks and Jiyeon Lee contributed to this report.