SEOUL-South Korea stands ready to respond to further provocations from North Korea, the presidential Blue House said on Saturday, as an ultimatum loomed for Seoul to halt anti-Pyongyang propaganda broadcasts by late afternoon or face military action.
Tension on the Korean peninsula has been running high after an exchange of artillery fire on Thursday, prompting calls for calm from the United Nations, the United States and the North's lone major ally, China.
North Korea, technically still at war with the South after their 1950-53 civil conflict ended in a truce, not a treaty, hasdeclared a "quasi-state of war" in front-line areas and set a deadline of 5 p.m. Pyongyang time (0830 GMT) for Seoul to halt the broadcasts from loudspeakers along the border.
Seoul says it will continue the broadcasts unless the North accepts responsibility for landmine explosions this month in the Demilitarised Zone (DMZ) that wounded two South Korean soldiers. Pyongyang denies it planted the mines.
A military source told South Korea's Yonhap News Agency on Saturday that there were signs the North Korean military was preparing to attack the loudspeakers, towing artillery to near the border. The defense ministry said it was checking the report.
"The Blue House is calmly observing the situation and ready to respond strongly against any additional provocations," a spokeswoman told Reuters.
North and South Korea have often exchanged threats over the years, and dozens of soldiers have been killed in clashes, yet the two sides have always pulled back from all-out war. Analysts expect this crisis eventually to wind down.
But the tension represents a blow to South Korean President Park Geun-hye's efforts to improve North-South ties, which have been virtually frozen since the deadly 2010 sinking of a South Korean warship. North Korea denies it was involved.
"The whole situation on the Korean peninsula has been bad for years now, because there's very little intra-Korean contact and that only makes a bad situation worse," said Joel Wit of 38 North, a North Korea monitoring project at Johns Hopkins University in Washington.