Marathon negotiations between North and South Korea dragged into a third day Monday, with the South demanding an apology and alleging unusual military activity from its northern neighbor.
The situation deteriorated earlier this month after land mines injured two South Korean soldiers. Seoul then began blasting propaganda from speakers along the border, followed by an apparent exchange of fire and North Korea saying Friday had entered a "quasi-state of war."
On the third day of talks to resolve the issue, South Korean President Park Geun-hye told her staff during a meeting Monday there was "no room to back down" and demanded an apology for the injured soldiers, according to government officials.
North Korea denies both planting the mines and firing on the South's propaganda speakers last week.
On Sunday, a South Korean defense official reported "unusual" military activity, saying North Korean submarines had left their bases, and the country had "doubled artillery power along the border."
The North has also deployed around 20 hovercraft and "ratcheted up its combat readiness," military sources in Seoul told the country's Yonhap news agency Monday.