That was then: In this file photo taken on September 14, 2018, South and North Korean officials attend an opening ceremony of a joint liaison office in Kaesong. North Korea blew up the office – on its side of the border – on Tuesday. Photo: AFP / Korea Pool

North Korea blew up an inter-Korean liaison office on its own side of the border on Tuesday, the South’s Unification ministry said. The move followed days of increasingly virulent rhetoric from Pyongyang.

“North Korea blows up Kaesong Liaison Office at 14:49,” the ministry, which handles inter-Korean relations, said in a one-line alert sent to reporters.

The statement came minutes after an explosion was heard and smoke seen rising from the long-shuttered joint industrial zone in Kaesong where the liaison office was situated, Yonhap news agency reported citing unspecified sources.

Its destruction came after Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, said at the weekend: “Before long, a tragic scene of the useless north-south joint liaison office completely collapsed would be seen.”

Since early June, North Korea has issued a series of vitriolic condemnations of the South over activists who send anti-Pyongyang leaflets over the border – something defectors do on a regular basis.

Last week it announced it was severing all official communication links with South Korea.

The leaflets – usually attached to hot air balloons or floated in bottles – criticize North Korean leader Kim Jong Un for human rights abuses and his nuclear ambitions.

Some analysts say Pyongyang may be seeking to manufacture a crisis to increase pressure on Seoul while nuclear negotiations with Washington are at a standstill.

In a photo taken in 2018 a South Korean soldier stands before a security fence at a guard post inside the Demilitarized Zone (DMZ) near the Military Demarcation Line (MDL) separating North and South Korea. The two sides agreed that year to eliminate guardposts but Pyongyang is now talking of remilitarizing the border. Photo: AFP/ Yelim Lee

Earlier Tuesday, North Korea’s army said it was “fully ready” to take action against the South, included re-entering areas that had been demilitarized under an inter-Korean agreement.

“North Korea is frustrated that the South has failed to offer an alternative plan to revive the US-North talks, let alone create a right atmosphere for the revival,” said Cheong Seong-chang, a director of the Sejong Institute’s Center for North Korean Studies.

“It has concluded the South has failed as a mediator in the process.”