SEOUL (Reuters) – North Korea lashed out at South Korea for the second day in a row on Friday, threatening to close an inter-Korean liaison office and calling the South naive to think the North wants dialogue and negotiations right now.

A spokesman for the United Front Department (UFD), which handles inter-Korea affairs, said North Korea would “definitely withdraw” from the liaison office operated with South Korean officials in the North Korean city of Kaesong as the first step in punishing the South for failing to stop defectors from sending leaflets across the border, according to a statement carried by state news agency KCNA.

The liaison office was one of several inter-Korea projects that were implemented during a period of detente between the two Koreas in 2018. Relations between the two countries have cooled again amid stalled talks over North Korea’s nuclear weapons.

“We do not hide that we have had long in mind decisive measures to fundamentally remove all provocations from the south and to completely shut down and remove all the contact leverage with the south side,” the spokesman said, calling defectors “mongrel dogs” and “human scum” who insulted the dignity of North Korea’s supreme leadership.

On Thursday, KCNA carried a similar statement by Kim Yo Jong, the sister of North Korea’s leader, warning South Korea over the leaflets, saying it may cancel a recent bilateral military agreement if the activity persists.

South Korean officials quickly responded to Kim’s statement, saying they make efforts to stop defector groups from sending leaflets, that the activities pose environmental risks and endanger private property in the South and raise tensions with the North, and suggested they may move to make such operations illegal.

South Korea’s Unification Ministry did not immediately respond to Friday’s statement by the UFD.

The UFD spokesman ridiculed South Korean officials, calling them “ignorant imbeciles” and “the meanest bastards” if they misunderstood or intentionally ignored the warnings in Kim’s statement.

“We are about to start the work that can hurt the south side soon to make it suffer from annoyance,” he said.