North Korea has blown up an inter-Korean liaison office building just north of the heavily armed border with South Korea in a dramatic display of anger that sharply raises tensions on the Korean peninsula.

The demolition of the building, which is located on North Korean territory and had no South Koreans working there, is largely symbolic, but it’s the most provocative thing North Korea has done since it entered nuclear diplomacy in 2018 after a standoff with the US had many fearing war.

It will pose a serious setback to the efforts of liberal South Korean President Moon Jae-in to restore inter-Korean engagement.

North Korea’s official Korean Central News Agency said the nation destroyed the office in a “terrific explosion” because its “enraged people” were determined to “force (the) human scum and those, who have sheltered the scum, to pay dearly for their crimes,” apparently referring to North Korean defectors who for years have floated anti-Pyongyang leaflets across the border.

The agency did not detail how the office in the North Korean border town of Kaesong was destroyed.

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Photos from the South’s Yonhap News Agency showed smoke rising from what appeared to be a complex of buildings.

The agency said the area was part of a now-shuttered inter-Korean industrial park where the liaison office was located.

The North also said it has cut off all government and military communication channels with the South while threatening to abandon bilateral peace agreements reached during North Korean leader Kim Jong Un’s three summits with Moon in 2018.

Some outside analysts believe the North, after failing to get what it wants in nuclear talks, will turn to provocation to win outside concessions because its economy has likely worsened because of persistent US-led sanctions and the coronavirus pandemic.

North Korea may also be frustrated because the sanctions prevent Seoul from breaking away from Washington to resume joint economic projects with Pyongyang.

North Korea had earlier threatened to demolish the office as it stepped up its fiery rhetoric over Seoul’s failure to stop activists from flying propaganda leaflets across the border.

On Saturday night, the influential sister of North Korea’s leader, Kim Yo-jong warned that Seoul will soon witness “a tragic scene of the useless North-South liaison office (in North Korea) being completely collapsed.”

She also said she would leave to North Korea’s military the right to take the next step of retaliation against South Korea.

Kim Yo-jong (centre) warned of the office’s fate.

North Korea has a history of taking highly visual symbolic steps.

It invited foreign journalists to watch the detonation of its underground nuclear testing tunnels in 2018 and the demolition of a cooling tower at its main nuclear complex in 2008.

Both events were an attempt by the North to show it was serious about denuclearisation amid rampant outside scepticism about its commitment.

Earlier Tuesday, North Korea’s military threatened to move back into zones that were demilitarised under inter-Korean peace agreements.

The General Staff of the Korean People’s Army said it was reviewing a ruling party recommendation to advance into unspecified border areas that had been demilitarised under agreements with the South, which would “turn the front line into a fortress”.

-AAP