As a result, the Korean People's Army (KPA) will reenter the border areas of Kaesong and Mount Kumgang, which were disarmed following a series of inter-Korean agreements.
Pyongyang declared on Wednesday that it had "flatly" rejected Seoul's previous offer to allow special envoys to assist in repairing tensions between the two Koreas, according to Yonhap News Agency, citing the North's state-run Korean Central News Agency (KCNA).
This follows the KPA's Tuesday declaration that it would "turn the front line into a fortress and further heighten the military vigilance against the South," following defectors' alleged dissemination of propaganda leaflets into North Korea.
Seoul proposed to settle the matter via legislation banning the activists' practice, but Pyongyang chose to instead carry out immediate, unilateral actions against South Korea and the "mongrel dog" defectors who betrayed their homeland.
The army noted in its KCNA statement that it would soon begin organizing an "action plan for taking measures to make the Army advance again into the zones that had been demilitarized under the North-South agreement."
The KPA's statement came alongside the destruction of the inter-Korean liaison office in Kaesong around 2:49 p.m. local time on Tuesday.
According to South Korean Deputy National Security Adviser Kim You Geun, North Korea's act of aggression against the Kaesong office “broke the expectations of all people who hope for the development of inter-Korean relations and lasting peace on the [Korean] peninsula."
"Closely following the attitude of the South Korean authorities, we will set the intensity for carrying out successive action measure against the enemy and the time for decisive actions in response to their subsequent demeanor and conduct," Pyongyang asserted Thursday, as reported by KCNA.
Inter-Korean relations have soured since the 2018 de-escalation agreement between South Korean President Moon Jae In and North Korean leader Kim Jong Un.
Though usual US-South Korea drills and other related military actions have fueled Pyongyang's criticism of Seoul, peninsular tensions have recently risen exponentially and North Korea has moved to sever all inter-Korean communications.
"The South Korean authorities connived at the hostile acts against the DPRK by the riff-raff, while trying to dodge heavy responsibility with nasty excuses. This has driven the inter-Korean relations into a catastrophe," Pyongyang's statement on the matter read.