North Korea has rejected South's Korea's proposal for talks on resuming reunions between families separated by the 1950s Korean War.
Seoul's Unification Ministry says the North delivered the message Thursday that a "proper atmosphere had not been created" to resume the talks.
A ministry spokesman, Kim Eui-do, said Seoul was disappointed in Pyongyang's decision.
"Our side considers it regrettable that North Korea has disagreed on our proposal for South and North Korean Red Cross negotiations on the fundamental solution to issues such as the regularization of separated families' reunions. As we have expressed a number of times, the issue of separated families is an assignment that must be resolved as a top priority in South-North Korean relations without connection to any other issue."
The North has often tried to tie the issue of family reunions to the resumption of other inter-Korean projects, such as restarting South Korean tours to its Mount Kumgang resort.
The family reunions were temporarily resumed last month for the first time in three years. The reunions followed rare high-level talks that had raised the possibility of an upswing in fragile Korean relations.
The North's rejection follows a series of short-range missile and rocket tests Pyongyang has carried out in response to large-scale U.S.-South Korean war drills.
The North on Wednesday described the launches as routine and defensive. It slammed the ongoing Key Resolve military exercise as provocative.
Washington and Seoul say their own drills are defensive, and say Pyongyang's tests are in violation of U.N. Security Council resolutions.
South Korea's Defense Ministry also provided more details Thursday about one of the North Korean rockets that narrowly missed a Chinese passenger airplane with over 200 people on board.
A spokesman, Kim Min-seok said Pyongyang did not give any advanced warning about the Tuesday launch.
"North Korea also committed serious threatening acts that ignored the prior navigational warning that was issued as part of the international order prescribed to protect the safety of civilians. Regarding this, our military is keeping a close watch on the possibility that North Korea's repeated and continuous provocative military actions could lead to actual provocation. We are making full preparations to respond sternly and strongly should there be provocation."
On Wednesday, South Korea's Defense Minister Kim Kwan-jin warned he "could not exclude the possibility" North Korea could soon conduct a nuclear or long-range missile test.
The developments are being watched closely by thousands of aging Koreans who have not seen or spoke to their relatives in decades.
South Korean President Park Geun-hye on Tuesday proposed allowing the separated families to communicate by way of letters and video messaging - though this, too, seems unlikely, given the North's rejection.
North and South Koreans are forbidden by their governments to correspond with one another. The two countries remain in a state of war following their 1950s conflict, which ended in a truce, not a peace treaty.