North Korea blows up liaison office just inside its border with the South

North Korea on Tuesday blew up a liaison office built with much fanfare two years ago near the border with rival South Korea. The dramatic display of antagonism came after days of increasingly barbed rhetoric and threats against the South.

The South Korean military confirmed the building had been destroyed with an explosion at 2:49 p.m. A column of billowing smoke was visible and an explosion was heard across the border from Kaesong, the North Korean town where the four-story liaison building was set up in 2018.

North Korea had just days earlier threatened destruction of the "useless" liaison office in a statement carried in state media from Kim Yo Jong, the sister of North Korean leader Kim Jong Un. The statement blamed South Korea for the stalemate in relations between the two sides.

The move also came after Pyongyang threatened to move troops closer to the demilitarized zone between the nations and to “turn the front line into a fortress.” Removing soldiers from the border area was part of previous military agreements between the leaders of the two Koreas.

Seoul warned North Korea that it would take measures if hostilities escalated.

"The North's destruction of the North-South joint liaison office is an act that let down the expectations of all those who hope for the improvement of relations between the Koreas and peace on the Korean peninsula," South Korea's National Security Council said in a statement. "If the North continues to take steps to worsen the situation, we will strongly respond accordingly."

North Korea in recent days had lambasted the South for the activities of North Korean escapees who send leaflets and flash drives with information into the isolated nation, criticizing Kim Jong Un and accusing the government of being a brutal dictatorship.

North Korean state media cited the escapees in a broadcast Tuesday about the explosion, calling them "human scum" and saying the move forced "those who have sheltered the scum to pay dearly for their crimes."

Observers say, though, that despite rhetoric directed at the refugees, the real intended audience may be Washington, to get the U.S. back to the negotiating table with North Korea before President Trump's term ends.

Talks between Trump and Kim to dismantle North Korea's nuclear program in exchange for relief from sanctions have netted no substantial agreements despite their three unprecedented face-to-face meetings. The North's already ailing economy is likely to be suffering even further this year after the country closed its border with China, its largest trading partner by far, out of coronavirus concerns.

The glass-fronted liaison building, north of the border in a dormant industrial complex that was once a hallmark of economic cooperation between the Koreas, was supposed to facilitate an unprecedented level of cross-border communication. South Korean offices were on the second floor and North Korean ones on the fourth, with regularly scheduled meetings in rooms on the third floor.

South Korean media reports said the building and support facilities cost about $15 million and were paid for by Seoul.

Dozens of South Korean officials staffing the office decamped in January, out of coronavirus concerns, with no announced plans for a return.