South Korea is warning of a "grave measure" if North Korea rejects a call for talks on a jointly run factory park that has been shut down for nearly a month.
Unification Ministry spokesman Kim Hyung-suk on Thursday refused to describe what Seoul would do if Pyongyang doesn't respond by a deadline Friday to a demand for formal working-level talks.
But Seoul may be signaling it will pull out its remaining workers from the factory across the border in Kaesong. That could lead to the end of a complex considered the last remaining symbol of inter-Korean cooperation.
(Read More: North Korea Warns Foreigners to Leave South)
Pyongyang suspended operations in early April and withdrew its 53,000 workers.
Pyongyang has recently eased the near daily threats it issued for several weeks. But tensions between the rivals are still high.