Update at 11:10 KST: This article has been updated to include a response from South Korea’s Ministry of National Defense (MND).

North Korea’s military on Tuesday promised to defy the terms of a 2018 inter-Korean military agreement and advance into previously demilitarized areas, as well as assist citizens in a retaliatory “large-scale leaflet scattering” campaign against the South.

In a statement carried by the Korean Central News Agency (KCNA), the General Staff of the Korean People’s Army (KPA) said it was keeping a “close watch” on growing inter-Korean tensions, sparked in part by Pyongyang’s fury at Seoul’s failure to stop activists from sending anti-regime leaflets into the North.

Saturday saw top official Kim Yo Jong warn the South that the North’s next step could be military action, saying that she had issued an order in the name of DPRK leader Kim Jong Un to the military.

The KPA said today that it had “accepted” an order from the country’s ruling party that would see it return troops to both ground and sea frontline positions.

“[We are] studying an action plan for taking measures to make the army advance again into the zones that had been demilitarized under the North-South agreement, turn the front line into a fortress and further heighten the military vigilance against the south,” said the statement.  “We also accepted an opinion on opening many areas in the ground front and southwestern waters.”

The army will also move to assist North Koreans in what appears to be a tit-for-tat campaign against activists sending leaflets North, it added.

The KPA, it said, would provide “security measure[s] for positively cooperating with our people from all walks of life in their large-scale leaflet scattering struggle against the enemy that is expected to take place.”

The plans are reportedly pending approval from North Korea’s top military decision-making body, the ruling party’s Central Military Commission (CMC), which is headed by leader Kim Jong Un.

Tuesday’s warnings, should they be put into action, would represent an effective end to the 2018 military agreement, signed by the two Koreas in September that year during a landmark summit in Pyongyang.

That agreement, once described by a top South Korean security official as a de facto “nonaggression pact,” aimed to reduce the chance of an inter-Korean active conflict by establishing a demilitarized buffer zone between the two.

The months following its signing saw the two Koreas decommission 20 guard posts (GPs) along their border, as well as suspend military drills within the area and designate a no-fly zone along the military demarcation line (MDL).

North Korea’s United Front Department (UFD) — charged with inter-Korean affairs — on Friday accused the South of “shattering” the accord — as well as the April 2018 Panmunjom declaration — through its failure to stop NGOs from sending anti-regime leaflets into its territory.

Kim Yo Jong — increasingly the North’s most prominent official dealing with relations with the South — followed up with a statement the next day, warning Seoul that an inter-Korean liaison office would soon be “collapsed.”

A growing domestic propaganda campaign has accompanied these warnings: ruling party daily the Rodong Sinmun on Monday carried a number of statements purportedly by enraged citizens keen to mete out revenge on the Southern “enemies.”

South Korea in response has called for calm, urging North Korea to stop escalating tensions and abide by its commitments under previous inter-Korean agreements.

In response to the KPA statement on Tuesday, South Korea’s defense ministry said it was “maintaining firm military readiness” and urged the North to abide by the military agreement.

“We do see that the efforts for keeping peace on the Korean peninsula that we have been putting should be sustained,” Ministry of National Defense (MND) spokesperson Choi Hyun-soo told press at a regular briefing.

“It is our basic stand that the September 19 military agreement must be complied with.”

Edited by Min Chao Choy