South Korea on Saturday urged North Korea to drop plans to send thousands of anti-South leaflets across the inter-Korean border, in a statement warning Pyongyang against further exacerbating rising tensions on the peninsula.

The comments, issued by the Ministry of Unification (MOU), follow reports in North Korean state media earlier in the day that efforts are now underway across the country to send “leaflets of punishment” to the South.

The move is reportedly in retaliation against Seoul’s failure to stop activists sending anti-regime leaflets into the DPRK.

“It is very regrettable that North Korean media today revealed the North’s plan to scatter anti-South leaflets in a large scale, and we urge it to stop immediately,” the Ministry of Unification (MOU) said.

“North Korea… must stop measures that further worsen the problem, and make effort for the peace on the Korean peninsula and development of South-North relations.”

Such a campaign, it continued, would represent a “clear” violation of agreements signed by the leaders of the two Koreas in 2018, and would only serve to worsen relations between the two.

Seoul, the statement said, had made efforts to crack down on balloon launches by activists — launches which have sparked outrage from North Korean officials and pushed inter-Korean relations to their tensest point in three years.

Those tensions, exacerbated further by North Korea’s decision on Tuesday to demolish an inter-Korean liaison office in the city of Kaesong, have also seen Pyongyang pledge to re-deploy soldiers to previously-demilitarized areas along the inter-Korean border.

The North Korean army has also promised to offer support to citizens in their plans to send “leaflet bombs of justice” across the inter-Korean border.

Those leaflets, state media on Saturday reported, are set to target both defector-activists and the South Korean government, which the North accuses of turning a blind eye to the leaflet launches.

“[They] outspokenly disclose and slam the criminal acts of the south Korean authorities which have been forsaken by the public mindset for terminating the inter-Korean relations and pursuing sycophancy toward the U.S.,” the Korean Central News Agency (KCNA) said.

“They are being piled as high as a mountain as if it was an eruption of the will of our people to imprint in the minds of enemies how excruciating the cost of their betrayal is,” it continued. “The south Korean authorities will face really horrible time.”

Imagery released by state media on Saturday revealed the leaflets will feature cartoons attacking South Korean President Moon Jae-in, as well as imagery of recent North Korean missile tests and indictments of prominent activists.

It is not clear when the leaflets will be sent, though North Korea has suggested they will go ahead as soon as soldiers are redeployed to “areas favorable for scattering anti-South leaflets.”

North Korean leaflets were in previous years regularly spotted on streets in and around Seoul, often carrying lurid propaganda condemning South Korean officials and praising the country’s nuclear program during periods of high tensions.

But the leafleting came to an end in April 2018, following an agreement by the two Koreas to stop the “distribution of leaflets” into each other’s territories.

Activists at the time promised to defy the ban, however, and continued to send flyers into the North.

Following over a year of worsening relations between the two Koreas, top official Kim Yo Jong early this month condemned a May 31 balloon launch by the defector-run Fighters for a Free North Korea (FFNK), demanding Seoul crack down on the “human scum” involved.

Tensions have only mounted since then, prompting the resignation of South Korea’s unification minister and warnings from Seoul that it will “not endure” further insults or aggression from the North.

And amid mounting concern over North Korea’s threats of military action, one NGO involved in sending leaflets to the North said it would call off weekend plans to send bottles carrying rice and leaflets into the North.

In a statement on Friday, Park Jung-oh, who heads the Keunsaem activist group, announced a planned Sunday launch would not go ahead.

“Considering how the South Korean citizens are worried due to Kim Jong Un and Kim Yo Jong’s lies and threats, we have decided to temporarily hold off the upcoming round of rice sending event,” he said.

“We are sorry for the North Korean residents — who are the victims of the North Korean dictatorship — waiting for the rice and hope.”