The North Korean army is ready to take action as defector groups advance their propaganda leaflet campaign to North Korea, the state media said on Tuesday in a recent warning of retaliation.
The General Staff of the Korean People's Army (KPA) said it was investigating an "action plan" to re-enter zones that had been demilitarized under a 2018 Inter-Korean Pact and "turn the front line into a fortress."
"Our army will implement all party and government decisions and orders quickly and thoroughly," the KPA said in a statement from the official KCNA news agency.
Tensions increased when Pyongyang threatened to break relations between Korea and retaliate against leaflets containing messages that criticize North Korean leader Kim Jong Un, including violations of human rights.
The Seoul Department of Defense urged Pyongyang to abide by the 2018 agreement, in which the military promised both sides to end "all hostile acts" and to dismantle a number of structures along the heavily fortified demilitarized zone between the two countries.
"We take the situation seriously," Choi Hyun-soo, spokeswoman for the ministry, said at a briefing. "Our military is ready to respond to any situation."
Several groups led by defectors have regularly returned flyers along with groceries, $ 1 bills, mini radios and USB sticks with South Korean dramas and news, usually by balloon over the border or in bottles by the river.
On Saturday, Kim Yo Jong, Kim's sister, who serves as a senior official of the ruling Labor Party, said she had ordered the military to prepare for an unspecified "next action".
South Korea plans to take legal action against two of the defector groups. Their actions fuel cross-border tensions, pose risks to residents living near the border, and cause environmental damage.
But the groups say they intend to continue their planned campaign this week.
South Korea's President Moon Jae-in called on Pyongyang on Monday to maintain the peace agreements between the two heads of state and government and to return to dialogue.
(Except for the headline, this story was not edited by NDTV staff and published from a syndicated feed.)